Associations between Plasma 25-Hydroxyvitamin D, Hormonal ... · Associations between Plasma...

Associations between Plasma 25-Hydroxyvitamin D, Hormonal Contraceptives, and Premenstrual Symptoms

by

Alicia Jarosz

A thesis submitted in conformity with the requirements for the degree of Master of Science (MSc)

Department of Nutritional Sciences University of Toronto

© Copyright by Alicia Jarosz 2017

ii

Associations between Plasma 25-Hydroxyvitamin D, Hormonal Contraceptives, and Premenstrual Symptoms

Alicia Jarosz

Master of Science (MSc)

Department of Nutritional Sciences

University of Toronto

2017

Abstract

Premenstrual symptoms are experienced by the majority of women and may cause significant

personal and professional impairment; however, little is known about their pathophysiology and

risk factors. The purpose of this thesis was to determine the prevalence of common premenstrual

symptoms in a multiethnic Canadian population and to explore the associations of plasma 25-

hydroxyvitamin D and hormonal contraceptive use with these symptoms. Symptom prevalence

was found to vary widely between common symptoms, ranging from 11% to 75%. Prevalence of

individual symptoms did not differ between ethnic groups, with the exception of cramps.

Hormonal contraceptive use was associated with a reduction in the risk of experiencing several

symptoms at moderate/severe severity. Plasma 25-hydroxyvitamin D was also inversely

associated with the prevalence and severity of several premenstrual symptoms. These findings

suggest HC use may be an effective targeted treatment and vitamin D status may be a risk factor

for individual premenstrual symptoms.

iii

Acknowledgments

First and foremost, I would like to thank my advisor Dr. Ahmed El-Sohemy for the

tremendous support and opportunities he has provided to me in the last two years. I am certain

that I could not have had a more encouraging supervisor. His guidance and knowledge were

crucial in helping me reach my academic and professional pursuits. Thank you, Ahmed. I had a

lot to learn as a young undergraduate student entering your lab and I am incredibly grateful for

your support and the countless learning opportunities you have created to encourage my

professional development.

I would like to thank my advisory committee, Dr. Joanne Kotsopoulos and Dr. Richard

Bazinet, for their guidance throughout the progression of this project. Their knowledgeable

advice and direction has benefited my thesis and their enthusiasm has encouraged me along the

way. Thank you, Dr. Kotsopoulos, for taking the time to help me with my academic writing. My

thesis and manuscripts have improved greatly thanks to you. I would also like to thank my

professors, Dr. Beatrice Boucher, Dr. Anthony Hanley, and Dr. Paul Corey. The research skills

they taught me in epidemiology and statistics helped me immensely with my thesis. Thank you,

Dr. Corey, for staying hours late after class to help me understand my data and find the best

statistical approach. Finally, thank you to Louisa Kung, who was always there to answer every

possible question I could have.

My time as a graduate student would not have been so enjoyable without my wonderful

El-Sohemy lab mates and colleagues in the Nutritional Sciences department. Thank you to

Ohood Alharbi, Neshat Deljoomanesh, Nanci Guest, Riva Sorkin, Sara Mahdavi, Joseph Jamnik,

Bryn Dhir, Katie Edmonds, and Daniel Noori. I am grateful to have had the chance to work

alongside such kind, helpful, and entertaining lab mates. I will forever look back fondly at the

iv

time we spent together. Thank you to my ‘honorary advisor’, Joseph Jamnik, for teaching me

everything I needed to know about SAS and TNH. You were there to help me through every

research obstacle I encountered and I could not have done this without you.

In many ways, I consider my successful completion of this thesis a team effort with my

friends and family who have supported me every step of the way. I would like to thank everyone

who has been a source of support and encouragement, and with whom I have celebrated all the

small accomplishments along this journey. I would especially like to thank my dad and sister,

Jerzy and Isabel, who have always been my biggest supporters in the pursuit of my educational

and career dreams. I would also like to thank my boyfriend, Razvan, for his unfaltering support

throughout my entire university education. You have all gotten me through the stressful and

hectic moments that are an inevitable part of any worthwhile endeavor, and celebrated my

triumphs as if they were your own. This accomplishment is as much yours as it is mine, and I am

eternally grateful to you all.

v

Table of Contents

Abstract ........................................................................................................................................... ii

Acknowledgments .......................................................................................................................... iii

Table of Contents ............................................................................................................................ v

List of Tables ............................................................................................................................... viii

List of Figures ................................................................................................................................ ix

List of Abbreviations ...................................................................................................................... x

Chapter 1 Introduction ........................................................................................................... 11

1.1 Introduction ......................................................................................................................... 1

1.2 Premenstrual Symptoms ..................................................................................................... 1

1.2.1 Premenstrual Disorders ........................................................................................... 1

1.2.2 Etiology ................................................................................................................... 3

1.2.3 Treatment ................................................................................................................ 6

1.2.4 Risk Factors ............................................................................................................ 7

1.3 Hormonal Contraceptives ................................................................................................... 8

1.3.1 Introduction ............................................................................................................. 8

1.3.2 Mechanisms of Action ............................................................................................ 9

1.3.3 HCs and Premenstrual Symptoms ........................................................................ 10

1.4 Vitamin D .......................................................................................................................... 12

1.4.1 Background ........................................................................................................... 12

1.4.2 Vitamin D Metabolism ......................................................................................... 13

1.4.3 Functions of Vitamin D ........................................................................................ 14

1.4.4 Determinants of Vitamin D Status ........................................................................ 15

1.4.5 Measurement of 25(OH)D .................................................................................... 17

1.4.6 Vitamin D and Premenstrual Symptoms ............................................................... 18

1.5 Summary and Rationale .................................................................................................... 19

vi

1.6 Hypothesis and Objectives ................................................................................................ 20

Chapter 2 Prevalence of Premenstrual Symptoms and Associations with Use of

Hormonal Contraceptives ......................................................................................................... 21

2.1 Abstract ............................................................................................................................. 22

2.2 Introduction ....................................................................................................................... 24

2.3 Methods ............................................................................................................................. 25

2.3.1 Study Population ................................................................................................... 25

2.3.2 Hormonal Contraceptive Use ................................................................................ 26

2.3.3 Anthropometrics and Physical Activity ................................................................ 26

2.3.4 Premenstrual Symptoms ....................................................................................... 26

2.3.5 Plasma Samples and Vitamin D Measurement ..................................................... 27

2.3.6 Statistical Analysis ................................................................................................ 27

2.4 Results ............................................................................................................................... 28


2.4.2 Prevalence of Premenstrual Symptoms ................................................................ 32

2.4.3 Premenstrual Symptom Associations with HC use .............................................. 35

2.5 Discussion ......................................................................................................................... 47

Chapter 3 Association between Plasma 25-Hydroxyvitamin D and Premenstrual

Symptoms ............................................................................................................................... 52

3.1 Abstract ............................................................................................................................. 53

3.2 Introduction ....................................................................................................................... 54

3.3 Materials and Methods ...................................................................................................... 55


3.3.2 Hormonal Contraceptive Use ................................................................................ 55

3.3.3 Anthropometrics and Physical Activity ................................................................ 55

3.3.4 Premenstrual Symptoms ....................................................................................... 55

3.3.5 Plasma Samples and 25-Hydroxyvitamin D Analysis .......................................... 56

vii

3.3.6 Food Frequency Questionnaire ............................................................................. 56

3.3.7 Statistical Analysis ................................................................................................ 57

3.4 Results ............................................................................................................................... 57

3.5 Discussion ......................................................................................................................... 65

Chapter 4 Synopsis, Limitations and Future Directions ........................................................ 69

4.1 Synopsis ............................................................................................................................ 70

4.2 Limitations ........................................................................................................................ 71

4.3 Future Directions .............................................................................................................. 73

References ..................................................................................................................................... 74

Appendices .................................................................................................................................. 104

viii

List of Tables

Table 2-1 Subject Characteristics Stratified by Hormonal Contraceptive (HC) Use1,2 ................ 30

Table 2-2 Subject Characteristics Stratified by Hormonal Contraceptive (HC) Use1,2 ................ 31

Table 2-3 Premenstrual Symptom Prevalence by Ethnicity ......................................................... 33

Table 2-4 Associations between HC Use and Premenstrual Symptom Severity .......................... 37

Table 2-5 Associations between Duration of HC Use and Premenstrual Symptoms ................... 42

Table 3-6 Subject Characteristics Stratified by Vitamin D Status1,2 ............................................ 59

Table 3-7 Associations between Plasma 25-Hydroxyvitamin D and Premenstrual Symptom

Severity ......................................................................................................................................... 61

Table A-1 GHLQ Premenstrual Symptom Questionnaire .......................................................... 104

ix

List of Figures

Figure 2-1 Associations between HC Use and Mild Premenstrual Symptoms ............................ 40

Figure 2-2 Associations between HC Use and Moderate/Severe Premenstrual Symptoms ......... 41

Figure 2-3 Associations between Duration of HC Use and Mild Premenstrual Symptoms ......... 45

Figure 2-4 Associations between Duration of HC Use and Moderate/Severe Premenstrual

Symptoms ..................................................................................................................................... 46

Figure 3-5 Associations between Plasma 25-Hydroxyvitamin D and Premenstrual Symptom

Severity1,2 ...................................................................................................................................... 64

x

List of Abbreviations

PMD - Premenstrual Disorder

PMS - Premenstrual Syndrome

PMDD - Premenstrual Dysphoric Disorder

ACOG - American College of Obstetricians and Gynecologists

GnRH - Gonadotropin-releasing hormone

CNS - Central nervous system

CRP - C-reactive protein

IL - Interleukin

PTH - Parathyroid hormone

1,25(OH)D - 1,25-hydroxyvitamin D

25(OH)D - 25-hydroxyvitamin D

SSRI - Selective serotonin uptake inhibitor

BMI - Body mass index

RCT - Randomized control trial

HC - Hormonal contraceptive

OC - Oral contraceptive

COC - Combined oral contraceptive

FSH - Follicle stimulating hormone

LH - Luteinizing hormone

DMPA - Depot medroxyprogesterone

UV - Ultraviolet

DBP - Vitamin d binding protein

VDR - Vitamin d receptor

RAAS - Renin-aldosterone-angiotensin-system

VTE - Venous thromboembolism

11

Chapter 1 Introduction

1.1 Introduction

Premenstrual symptoms are a collection of physiological, behavioral, and psychological

symptoms that occur during the late luteal phase of a woman’s reproductive cycle. They are

characterized by their timing and by their cyclic nature, while the nature, number, and severity of

the symptoms varies between women1. Hundreds of symptoms have been described to date,

however, the most commonly experienced somatic symptoms are bloating, headache, fatigue,

and muscle cramps. Behavioral and psychological symptoms are also commonly experienced,

such as anxiety, mood swings, changes in appetite, and depression2.

The prevalence of experiencing premenstrual symptoms is estimated to be 85-98%, while

prevalence of individual symptoms varies widely between studies and populations2. The social

and economic burdens of premenstrual disorders are substantial. It is estimated that premenstrual

syndromes result in an increase of $59 and $4333 in American women’s individual direct and

indirect healthcare costs, respectively3. Furthermore, women with moderate or severe

premenstrual symptoms work fewer days and have reduced productivity compared to those

without symptoms3-5. Although premenstrual symptoms and disorders are common, there are few

treatments available for them and little research exists on the topic of dietary influences and risk

factors2. It is generally accepted that prevalence of premenstrual symptoms is influenced by

subject characteristics such as BMI, physical activity, and age, however, the effect of

race/ethnicity is inconsistent6.

1.2 Premenstrual Symptoms

1.2.1 Premenstrual Disorders

Premenstrual disorders (PMDs) are a group of disorders sharing the commonality of

regularly occurring premenstrual symptoms and include Premenstrual Syndrome (PMS) and

2

Premenstrual Dysphoric Disorder (PMDD). Diagnosis of PMDs requires that premenstrual

symptoms are linked to the luteal phase. Symptoms must begin during the late luteal phase and

resolve within a few days following the onset of menses, with a clear symptom free interval

between cycles. The nature or number of the symptoms is not important, so long as the timing

and cyclicity criteria are met. PMDs are diagnosed prospectively using symptom diaries where

patients record their symptoms daily for at least 2 months. Differential diagnosis must also be

excluded, as premenstrual symptoms must be differentiated from exacerbations of underlying

disorders1.

PMS diagnosis criteria are defined by the American College of Obstetricians and

Gynecologists (ACOG)7. They require that 1 somatic and 1 affective symptom to be experienced

at moderate or severe severity for at least 2 consecutive cycles recorded by prospective

recording. Somatic symptoms include: bloating, breast tenderness, headache, joint or muscle

pain, swelling of extremities, and weight gain. Affective symptoms include: angry outbursts,

anxiety, confusion, depression, irritability, and social withdrawal. Symptoms must begin 5 days

prior to menses, subside within 4 days following the onset of menses, and be followed by at least

12 symptom-free days. Symptoms must be recorded in the absence of any pharmacological or

hormonal therapy, without use of drugs or alcohol, and be met with identifiable dysfunction in

everyday activities such as social or work related activities7. PMS has been estimated to occur in

20-32% of women1.

The most severe PMD is premenstrual dysphoric disorder (PMDD) which is defined in

the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM

IV)8. PMDD requires experiencing at least 5 premenstrual symptoms, with at least one affective

symptom at moderate/severe severity. Similar to PMS criteria, symptoms must cause identifiable

dysfunction in social or work activities, they must not be an exacerbation of other disorders, and

3

must be confirmed using prospective symptom recording for 2 consecutive cycles. Prevalence of

PMDD has been found to be between 3-8%1.

1.2.2 Etiology

The etiology of premenstrual symptoms is not well understood, however, prevailing

theories attribute the occurrence of premenstrual symptoms to women’s individual responses to

normal fluctuations in gonadal steroid production that occur during the reproductive cycle9.

Premenstrual symptoms are absent during non-ovulatory cycles, menopause, pregnancy, and

following oophorectomy10, when production of the corpus luteum does not occur thus

eliminating rises in estrogen and progesterone in the luteal phase. Increased severity of

symptoms is likely due to the sensitivity of some women to changes in hormone production,

rather than to differences in hormone concentrations11. Premenstrual symptoms are absent during

pregnancy despite high levels of both estrogen and progesterone, and concentrations of these

hormones have not been shown to differ between those with PMS compared to controls.

However, inducing a chemical menopause using gonadotropin-releasing hormone (GnRH)

agonist was shown to abolish symptoms in women with PMS11. Following this GnRH agonist

treatment with introduction of exogenous estrogen or progesterone caused symptoms to return in

women with PMS but not in controls11. This work strongly suggests the occurrence of

premenstrual symptoms to be a result of abnormal responses to normal hormonal fluctuations

during the luteal phase.

Estrogen and progesterone, as well as their metabolites, are involved in the regulation of

various physiological processes in the body, some of which have been theorized to be implicated

in the pathophysiology of PMDs. Progesterone is metabolized in the brain and ovary to form

neuroactive steroids 3-alpha-hydroxy-5-alpha-pregnane-20-one (ALLO) and 3-alpha-hydroxy-

5beta-pregnane-20-one (pregnanolone)12. ALLO and pregnanolone act as positive allosteric

4

modulators of the GABA neurotransmitter system. GABA receptors are widely distributed in the

central nervous system (CNS) and are important regulators of anxiety, alertness, stress, and

vigilance12. ALLO binds GABAA receptors and alters their sensitivity to neurosteroids, making

them temporarily insensitive to GABA12. Acute ALLO treatment has been shown to produce

anxiolytic and antidepressant effects in the short term, however, long term exposure has been

shown to increase anxiety13. PMS women have been found to have reduced luteal phase ALLO

concentrations compared to controls and some studies have shown an association with

premenstrual mood symptoms14, 15.

The serotonergic system has also been implicated for its role in PMS. Premenstrual

symptoms are very similar to those experienced with reduction of serotonin transmission, such as

mood swings, anxiety, depression, irritability, carbohydrate cravings, and difficulty

concentrating16. Ovarian sex steroids are involved in the metabolism of serotonin, as well as its

turnover, uptake, binding, and transport16. Animal studies have demonstrated increased whole-

brain serotonin as well as increased serotonin synthesis and decreased re-uptake in the midbrain,

hypothalamus, and amygdala in rats following acute and chronic ethynyl estradiol

administration17-19. Serotonergic function has been found to be altered during the luteal phase in

PMS women compared to controls, with PMS women having reducing platelet uptake of

serotonin and lower whole-blood serotonin levels20, 21. The high efficacy of selective serotonin

reuptake inhibitors (SSRIs) in the treatment of PMS and PMDD22 further supports the

involvement of the serotonergic system in PMDs.

In addition to theories of neurotransmitter involvement in the etiology of PMDs,

inflammation has also been linked to the occurrence of premenstrual symptoms. Multiple studies

have demonstrated an association between increased inflammatory markers such as c-reactive

protein (CRP), and pro-inflammatory cytokines including interleukin (IL)-2, IL-4, IL-10, IL-12,

5

and interferon-gamma in PMS women compared to controls23-25. The observed increase in CRP

found in PMS women was reproduced in another cross-sectional study and associated with

symptoms of anxiety and mood changes, muscle aches and cramps, increased appetite and

bloating, and breast pain26. Inflammation has a plausible role in the development of premenstrual

symptoms as it is already involved in other aspects of reproductive function such as ovulation,

endometrial repair, and follicular recruitment27. Inflammatory markers, such as CRP, IL-6, IL-

1β, and tumor necrosis factor-α, fluctuate throughout the female reproductive cycle with rises in

concentration following ovulation and peaking during menstruation28.

It has been suggested that some premenstrual symptoms may occur as a result of

dysregulation in calcium homeostasis and secondary hyperparathyroidism29. Serum calcium,

parathyroid hormone (PTH), and 1,25-hydroxyvitamin D (1,25(OH)D) have been shown to

fluctuate across the menstrual cycle30, 31. Serum calcium levels drop at three stages of the

menstrual cycle: during menses, midcycle, and during the late luteal phase30. Fluctuations in

these hormones may differ in women with PMDs, as suggested by two studies, one of which

demonstrated that women with PMDD had significantly different fluctuation patterns from

controls in 1,25(OH)D, ionized calcium, and urinary calcium30. Similarly, menstrual cycle

fluctuations in PTH, 25(OH)D, and 1,25(OH)D were found to differ in PMS women compared to

controls32. PTH showed midcycle elevations in PMS women but not controls, suggesting that

they may be experiencing transient, secondary hyperparathyroidism32.

Higher calcium intake may be protective against these fluctuations, as multiple studies

have reported decreased calcium intake in women with PMDs compared to controls33, 34.

Furthermore, clinical studies have demonstrated calcium supplementation reduces the severity of

premenstrual symptoms35-39. There are similarities between hypocalcaemia symptoms and

common premenstrual symptoms, such as those of anxiety, depression, fatigue, impaired

6

intellectual capacity, personality disturbances, and muscle cramps29. Further supporting the

hypothesized involvement of calcium in PMS etiology is the observed increased risk of

osteoporosis after menopause in women with PMS40, 41.

1.2.3 Treatment

The current first line treatment for PMDs is the use of selective serotonin uptake

inhibitors (SSRIs)42. Studies have demonstrated a reduction in premenstrual symptoms with the

use of SSRIs with a response rate of 60-90%43. A 2013 Cochrane review analyzing 31 RCTs

found that continuous or luteal-phase SSRIs are effective for premenstrual symptom relief

compared to placebo44. SSRIs have been shown to effectively reduce both premenstrual mood

symptoms as well as somatic symptoms such as bloating, breast tenderness, and appetite

changes45. SSRI’s are, however, are accompanied by many adverse side effects such as nausea,

fatigue, and decreased libido44 which may make them unsuitable treatment options for some

women.

PMDs may also be effectively treated by inhibiting ovarian cyclicity through the use of

GnRH agonists or through bilateral oophorectomy43, 46. GnRH agonists act by interrupting the

normal pituitary-hypothalamus-gonadal cyclicity which triggers ovulation and premenstrual

symptoms. GnRH agonists are considered quite effective in treating somatic and psychological

premenstrual symptoms46 but result in a medically-induced menopause which is accompanied by

menopausal symptoms that must also be managed9. Furthermore, to reduce the risk of

cardiovascular disease and hypoestrogenic bone loss resulting from long-term GnRH agonist use,

add-back therapy with estrogen and progesterone must often be added which risks reintroducing

premenstrual symptoms2. Surgical bilateral oophorectomy is also effective in abolishing

premenstrual symptoms47 but is considered too invasive of a procedure for a majority of

7

patients9. Although SSRIs and GnRH agonists are effective in treating PMDs, they are either

highly invasive or likely to cause severe adverse effects. Consequently, more research into

potential therapies and the etiology of premenstrual symptoms is necessary to develop much

needed novel therapeutic remedies.

Other treatments may be considered when managing premenstrual symptoms such as

lifestyle changes to reduce stress and increase exercise, calcium supplementation, hormonal

contraceptives, anxiolytics, and herbal preparations2. Although there is some evidence for the

efficacy of these treatments, there is not enough evidence to conclude they are effective in

treating premenstrual symptoms2.

1.2.4 Risk Factors

Several factors have been identified that put women at risk for experiencing premenstrual

symptoms or disorders, and these include age, body mass index (BMI), and physical activity.

Regular physical activity is considered a protective factor against premenstrual symptoms and

has been inversely associated with the severity of premenstrual symptoms in several

epidemiological studies48, 49, as well as randomized control trials (RCT)50-52. For example, a

recent RCT demonstrated the efficacy of engaging in regular aerobic exercise three times per

week for reducing several individual premenstrual symptoms in young women50.

BMI has been similarly associated with premenstrual symptoms, where those with higher BMI

were more likely to be experiencing symptoms at greater severity53. This was especially

pronounced in obese women with BMIs greater than 27.5 kg/m254, 55. Lastly, increasing age may

be a risk factor for premenstrual symptoms, with symptom prevalence peaking at age 366.

Ethnic background may also be a contributing risk factor to premenstrual symptomology,

however this has not been consistently shown. A couple studies have shown differences in the

8

prevalence of premenstrual symptoms between Caucasian and African American women living

in America, where Caucasians reported a lower prevalence of some symptoms56, 57. Similarly,

Asians have reported a lesser severity of premenstrual symptoms relative to Caucasians in a

previous study58. However, some cross-sectional studies have not observed any ethnic

differences in the prevalence of premenstrual symptoms or PMS. The reason for these ethnic

differences in prevalence of symptoms is not known. It is hypothesized that they may be due to

underlying genetic or cultural differences58, 59.

1.3 Hormonal Contraceptives

1.3.1 Introduction

Hormonal contraceptives (HC) are formulations of synthetic estrogen and progesterone

derivatives which prevent ovulation. They were first introduced to the North American market in

the 1960’s as combined oral contraceptives containing first-generation estrogen and progesterone

analogues60. Since that time, their formulations have evolved to include options containing

second and third-generation analogues as well as various modes of administration. Rather than

taken orally, HCs can now also be administered in skin patches, intra-muscular injections,

implants, vaginal rings, or intra-uterine systems. There are numerous HC options available on the

Canadian market, whose formulations differ in dose and type of estrogen or progestin used. Oral

contraceptives (OC) are used by 16% of Canadian women and are the most common form of HC

used in Canada 61. OCs typically contain both an estrogen and progestin (called a combined oral

contraceptive (COC)) but may also be composed of only progestin (called a progestin-only pill).

Contraceptives were first created to mimic the natural 28-day ovarian cycle by administering

COCs for 21 days, followed by 7 days of a dose-free interval during which menstruation took

place. However, COCs can also be taken in extended or continuous regimens which delay or

eliminate menstruation, respectively. Their formulations may be monophasic, in which the

9

estrogen or progestin dose remains constant, or biphasic or triphasic, in which the estrogen or

progestin are administered in two or three different doses throughout the cycle, respectively.

Biphasic and triphasic regimens have formulations which periodically increase the dose of

estrogen of progestin, and were created with the intention of reducing the amount of exogenous

hormones administered.

1.3.2 Mechanisms of Action

Although the forms of HCs are varied, they are united in their primary mechanism of

action being their ability to inhibit ovulation by exerting an inhibitory effect at the hypothalamic

and pituitary levels 62. COCs block the normal production of GnRH and may also act directly on

the pituitary gland63. This exerts an inhibitory effect on the production of follicle-stimulating

hormone (FSH) and luteinizing hormone (LH) in the pituitary gland, especially on the midcycle

surge of these hormones which would typically induce ovulation64. These effects inhibit the

production of new follicles during the follicular phase and ovulation62. This prevents the

development of the corpus luteum and thus the luteal phase rise in estrogen and progesterone.

The progestin component of the COCs is especially effective at preventing this midcycle rise in

LH. The estrogen component of the COC amplifies this effect in addition to preventing irregular

shedding of the endometrium62, 65. FSH and LH secretion returns immediately following the

discontinuation of COCs. In fact, follicles begin to develop again during the 7-day dose-free

interval66.

Other forms on HCs have similar mechanism of action to COCs whereby they suppress

follicular development and inhibit ovulation. It is not necessary to administer both estrogen and

progestin to suppress ovulation, as either on its own is sufficient to inhibit pre-ovulatory spikes

in FSH and LH and thus prevent ovulation62. The most commonly used progestin-only injectable

contraceptive is depot medroxyprogesterone (DMPA). This long-acting progestin interrupts

10

ovulation by mechanisms similar to those of COCs, where it prevents the midcycle LH surge by

acting at hypothalamic and pituitary levels67. HCs also prevent pregnancy through secondary

mechanisms such as thickening of the cervical mucus, affecting peristalsis and secretion within

the fallopian tube, and by affecting the uterine lining making it unsuitable for implantation68-72.

HCs also exert several other biologic effects in the body that are unrelated to their

contraceptive action. HCs have been shown to impact bone mass73, vitamin D status74, the

cardiovascular system75-77, cognitive outcomes78, inflammatory markers79, as well as many other

physiological processes. Their physiological effects can be dependant on the type of HC used.

For example, while COCs have been associated with increased 1,25-hydroxyvitamin D

concentrations due to the estrogenic effect on vitamin D metabolism, formulations containing

medroxyprogesterone acetate did not exert the same effects on 1,25-hydroxyvitamin D

concentrations. HC formulations using newer formulations also have a more net-estrogenic effect

than early generation progestins since the new progestins have very little androgenic activity80, 81,

and also exert an anti-aldosterone effect82.

COCs have also been associated with increased risk of adverse cardiovascular outcomes,

such as increased risk of venous thromboembolism (VTE) and altered lipid profiles75, 83, 84. This

effect is also dependent on the COC formulation used, as rates of VTE differ between

formulations75, 76, 85. There is also evidence that these cardiovascular outcomes may be dependent

on the duration of use of hormonal contraceptives. Risk of VTE is highest in the first few months

of use and then declines75, 84. Similarly, total serum lipids are observed to increase with the start

of HC use but return to baseline following 24 months of use83.

1.3.3 HCs and Premenstrual Symptoms

Hormonal contraceptive use may be effective in treating premenstrual symptoms by

preventing ovulation and stabilizing fluctuations in estrogen and progesterone during the luteal

11

phase. Since premenstrual symptoms have been observed to be absent during non-ovulatory

cycles9, preventing ovulation may be an effective therapeutic strategy for premenstrual

syndromes. This relationship, however, is complicated by the addition of exogenous estrogens

and progestins with HCs as well as by the minor fluctuations in hormones that occur during the

pill-free days9. This is supported by evidence showing the comparatively improved efficacy of

extended HC regimens in treating premenstrual symptoms86. Due to their widespread use and the

inconsistency of the available research it is important to determine whether HCs are useful in

treating premenstrual symptoms and, if so, for which symptoms they are effective.

The few placebo-controlled randomized trials that have been conducted on this topic have

obtained mixed results. Some randomized control trials (RCTs) did not find HCs to be effective

in treating premenstrual symptoms87, 88, while others found them to be effective for some

premenstrual symptoms but not others89, 90. Numerous open-label studies found hormonal

contraceptives to be effective in decreasing the severity of some premenstrual symptoms, but not

all91-93. There is also evidence that more recent HC formulations may be more effective in

treating premenstrual symptoms than older formulations, such as those containing

drospirenone94.

Observational studies conducted on the topic and have also obtained conflicting results.

Three large observational studies have found a substantially lesser prevalence of premenstrual

symptoms in women using HCs compared to non-users58, 95. An analysis of a health maintenance

organization found an inverse relationship between hormonal contraceptive use and both the

number and severity of emotional premenstrual symptoms (p<0.01), but not physical

symptoms58. Similarly, investigations of a large multiethnic US cohort of premenopausal women

as well as a large French cohort showed significantly lower prevalence of PMS in HC users96, 97.

Conversely, a small nested case-control study within a US cohort found no difference in total

12

symptom prevalence between HC users and non-users98. Furthermore, one study instigating

premenstrual symptom associations with HC use among women with PMDD found an increase

in the prevalence of some individual symptoms in HC users compared to non-users99. Symptoms

that were more prevalent among HC users included: anxiety, anger, avoided social activities,

weight gain, joint/muscle pain, and difficulty concentrating99. Novel studies assessing the effects

of newer HC formulations on individual premenstrual symptoms may elucidate the conflicting

findings.

To date, no studies have investigated whether duration of HC use plays a role in their

effect on premenstrual symptoms. The effects of HCs on risk of VTE, lipid profiles and

cholesterol metabolism have been shown to be related to be dependent on duration of HC use75,

83, 84, 100. The decline in VTE risk occurs after a few months75, 84 and lipid profiles return to

baseline after two years84, although the mechanisms for this are unknown. Current trials

investigating the effect of HCs on premenstrual symptoms have been conducted no longer than

6-8 months. It is possible that HCs may become more or less effective in the treatment of

premenstrual symptoms with time.

1.4 Vitamin D

1.4.1 Background

Vitamin D status is determined by a combination of dietary Vitamin D consumption and

cutaneous production101. Since vitamin D can be synthesized in the skin with sun exposure and it

is not necessary to obtain it in the diet, it is technically a prohormone rather than a vitamin102. It

is produced in the skin phytochemically from 7-dehydrocholesterol and has a structure similar to

that of classic steroid hormones such as estradiol, aldosterone, and cortisol102. Vitamin D is

found in two forms- ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Ergocalciferol

and cholecalciferol are very similar in structure, the only difference being the existence of a

13

double bond at carbons 22-23 and a methyl group on carbon 24 in ergocalciferol103.

Ergocalciferol is obtained from plant and fungal sources while cholecalciferol can be obtained

from animal sources or endogenous production, and both are found in supplements102.

Although vitamin D may be obtained from the diet, most circulating vitamin D is derived from

cutaneous production104. Those living in Canada are at risk of vitamin D deficiency resulting

from inadequate sun exposure due to its high latitude101. According to the most recent Canadian

Health Measures Survey (CHMS), a third of Canadians had vitamin D levels below the cut-off

for sufficiency, and this number increased to about 40% during wintertime months105. In

response to the widespread vitamin D deficiency in Canada, laws now mandate the fortification

of margarine, milk and plant-based beverages with vitamin D101. Nevertheless, dietary vitamin D

consumption accounts for about 148–236 IU of daily vitamin D104 which in Canada is mostly

derived from fortified dairy products and fruit juices101. Few foods naturally contain vitamin D,

the largest sources are eggs, liver, and oily fish which can provide 250-950 IU/serving106.

1.4.2 Vitamin D Metabolism

Vitamin D consumed in the diet is absorbed in the small intestine by enterocytes and

subsequently packed into chylomicrons with other lipids for delivery to the liver102, 107. While

ergocalciferol and cholecalciferol can be obtained from foods and supplements, cholecalciferol

can also be synthesized in the body103. 7-dehydrocholesterol is embedded in the plasma

membrane and is converted to previtamin D3 in response to ultraviolet (UV) B exposure. Since

previtamin D3 is thermodynamically unstable, it is quickly converted to cholecalciferol via

rearrangement of its double bonds103. As a consequence of this reaction, cholecalciferol is ejected

from the plasma membrane and diffuses into the dermal capillary. Here it becomes bound to its

transport protein, vitamin D binding protein (DBP), which has a very strong affinity for

cholecalciferol, and is transported to the liver103. In the liver, cholecalciferol is hydroxylated by

14

25-hydroxylase (CYP27A1) to form the main circulating vitamin D metabolite, 25-

hydroxyvitamin D (25(OH)D)108. 25(OH)D is thought to be biologically inert and its half-life is

about 3 to 4 weeks102, 109.

25(OH)D can be converted into its active form of 1,25-dihydroxyvitamin D (1,25(OH)D)

in the kidneys and other target tissues such as the brain102. This conversion is done by the

mitochondrial enzyme 1-hydroxylase (CYP27B1)102, 110. 1,25(OH)D is a steroid hormone which

regulates gene transcription and affects various signal transduction pathways through vitamin D

receptor (VDR) binding111. Its half-life is about 24 hours112. Unlike 25(OH)D, the production of

1,25(OH)D is very tightly regulated, with 1,25(OH)D and high calcium levels decreasing its

production and PTH and calcitonin increasing its production113. Low calcium levels cause an

increase in PTH production which leads to both and increase in 1,25(OH)D production as well as

increased calcium absorption in the intestine113, 114.

1.4.3 Functions of Vitamin D

Vitamin D is a fat-soluble vitamin which behaves like a steroid hormone. 1,25(OH)D

exerts a majority of its biological actions by binding to the vitamin D receptor (VDR) and

regulating gene transcription115. VDRs and CYP27B1 are expressed widely throughout the body,

suggesting that vitamin D has widespread roles in many biologic systems such as the immune

system, brain, bone, and skin116. It plays an important in bone health and regulating calcium

homeostasis. 1,25(OH)D stimulates calcium and phosphorous absorption in the intestine in

response to low calcium levels117. 1,25(OH)D stimulates the proliferation and differentiation of

osteoblasts, as well as increases bone mineralization118-120. Vitamin D deficiency is associated

with low bone mineral density and increased fractures101. It is also associated with decreased

falls121, 122, which is attributed to improvements in muscle strength and lower-extremity function

15

with vitamin D supplementation123. VDRs are located on fast-twitch muscle fibers124 and vitamin

D deficiency is associated with muscle weakness and myopathy125, 126.

In recent years, vitamin D research has extended to areas beyond the skeletal system

which has given some insight into its widespread effects in the body. Vitamin D appears to exert

beneficial effects on the cardiovascular system, where 25(OH)D has been inversely associated

with risk of heart disease and hypertension in several large observational studies127-130. These

cardiovascular effects of vitamin D are thought to be mediated by vasculoprotection, decreased

inflammation, beneficial effects on calcium homeostasis, and suppression of the RAAS131.

Vitamin D has shown anti-inflammatory properties in vitro132, 133 and has been associated with

lower levels of inflammation in some134-136, but not all137, 138, observational studies. Lastly,

vitamin D may be involved in disorders affecting the neurological system. 1,25(OH)D is a

neurosteroid which can cross the blood-brain barrier and act on most areas of the brain through

VDRs117, and vitamin D deficiency has been associated with depression and cognitive

impairment139, 140.

1.4.4 Determinants of Vitamin D Status

Vitamin D status can be influenced by several lifestyle, demographic, and biologic

factors. The main factors known to influence 25(OH)D levels include UV exposure, body

composition, dietary consumption, medications, ethnocultural status, and genetics. Since

cholecalciferol in synthesized in the body in response to UVB exposure, any factor affecting the

degree of UVB exposure can influence an individual’s vitamin D status. This includes time spent

outdoors, skin pigmentation, clothing, use of sunscreen, and environmental factors influencing

the strength of UVB radiation141. UVB radiation is diminished in environments with latitudes

farther from the equator, and is also affected by weather, time of day, altitude, and season141.

Generally, vitamin D can not be synthesized by those living in regions above 33˚ north latitude

16

during wintertime months of November to March or between the hours of 3pm and 10am142.

Similarly, increased skin pigmentation can act as a natural sunscreen by absorbing UVB rays and

prevent the synthesis of cholecalciferol143. For this reason, ethnic groups with increased skin

pigmentation produce less vitamin D in response to sun exposure and are at risk of vitamin D

deficiency144, 145. Dietary vitamin D intake can also contribute to circulating levels of 25(OH)D,

although, their correlations range from r=0.2 to r=0.7 suggesting that other factors are

contributing significantly to vitamin D status101, 146.

Other factors, such as body mass, genetics, and medication use, can also affect circulating

levels of 25(OH)D by affecting its bioavailability, sequestration, and rate of breakdown. Obesity

has been reported to be inversely associated with 25(OH)D in several cross-sectional studies147-

149 and this is thought to be the result of sequestration of vitamin D by adipose tissue149, 150.

Similarly, some common medications are known to affect vitamin D metabolism, such as those

containing sex-hormones151, 152. HC use is positively associated with 25(OH)D levels and it is

thought that this effect is mediated by the estrogen component74, 152, 153 Estrogen has been shown

in animal and in vitro studies to upregulate CYP27B1 and downregulate CYP24A1, enzymes

responsible for the conversion of 25(OH)D to 1,25(OH)D and the catabolism of 25(OH)D as

well as 1,25(OH)D, respectively154, 155. Estrogen is also associated with elevated DBP

concentrations and may upregulate VDR expression153, 156. A recent cross-sectional study found

HC users to have significantly higher 25(OH)D concentrations than non-users, who had similar

levels to men74. Finally, several common genetic variants along the vitamin D metabolic pathway

have been associated with vitamin D status including those in CYP27B1157, CYP24A1158, and

VDR159. Heritability estimates for plasma 25(OH)D concentrations based on twin studies range

between 45% and 75%160-162, suggesting genetic variation may be an important factor in

determining an individual’s vitamin D status.

17

1.4.5 Measurement of 25(OH)D

Vitamin D status is measured by serum concentrations of the main circulating vitamin D

metabolite, 25(OH)D, which is the best indicator of functional vitamin D status as it takes into

account contributions from dietary intake and cutaneous production163. In comparison to

1,25(OH)D, 25(OH)D has a much longer half-life, is present in much higher concentrations, and

its formation is not regulated, thus making it a better estimate of vitamin D status112.

Approximately 85% of 25(OH)D is bound to DBP, while 15% is bound to albumin and 0.03% is

free164.

There are several methods available for measuring 25(OH)D including by

radioimmunoassay (RIA), high-performance liquid chromatography (HPLC), and LC MS/MS112.

The strengths and limitations of each of these methods differ, but HPLC with UV detection and

LC MS/MS may be considered the gold standard methods because of their abilities to

differentiate between 25(OH)D2 and 25(OH)D3, their precision, and their accuracy165-167.

25(OH)D concentration cut points determining vitamin D status were suggested by the

Institute of Medicine (IOM), and according to these criteria, deficient, inadequate, and sufficient

vitamin D statuses correspond to plasma 25(OH)D concentrations of <30 nmol/l, 30–50 nmol/l,

and >50 nmol/l163. These criteria were largely based on maintaining optimal bone health163. The

IOM criteria for determining vitamin D status have been controversial and widely criticized as

overly conservative by not considering the important role of vitamin D in health outcomes

beyond bone metabolism168-170. Many investigators as well as the Canadian Osteoporosis Society

(COS) and the Endocrine Society (ES) have proposed that optimal vitamin D status should be

considered at 25(OH)D plasma concentrations >75 nmol/l101, 170-172.

18

1.4.6 Vitamin D and Premenstrual Symptoms

The evidence of calcium homeostasis dysregulation and luteal-phase calcium deficiency

playing a role in the etiology of premenstrual symptoms has prompted the investigation of

associations between vitamin D and premenstrual symptoms. It is proposed that vitamin D may

be protective again premenstrual symptoms through its involvement in the regulation of calcium

homeostasis29. Plasma calcium and 1,25(OH)D concentrations have been shown to fluctuate

during the menstrual cycle, with levels of calcium decreasing and 1,25(OH)D increasing during

the luteal phase30, 32. 25(OH)D concentrations were not shown to fluctuate throughout the

menstrual cycle30.

Alternative theories for the involvement of vitamin D in premenstrual symptoms include

its role in reducing inflammation as well as its direct effect on the brain. 1,25(OH)D can cross

the blood-brain-barrier and is capable of binding to VDRs located in the brain173-175. VDRs are

distributed throughout areas of the brain known to be involved in mood and psychologic

disorders, such as depression, which share common symptoms with PMS including depression,

loss of appetite, and insomnia173-175. Furthermore, vitamin D plays a role in immune regulation

and is associated with a reduction in inflammation176, 177. Since premenstrual symptoms have

been associated with elevated inflammatory markers26, vitamin D may reduce symptoms through

this pathway.

Investigations into the role of dietary vitamin D have shown relatively consistent inverse

associations between vitamin D intake and premenstrual symptoms. Analysis of the Nurse’s

Health Study II data has revealed an association between high dietary intake of vitamin D and a

decreased risk of PMS33. High vitamin D intakes have also been associated with decreased

severity of premenstrual symptoms in the general population178. Few studies have examined the

association between vitamin D status and premenstrual symptoms, but those that have report

19

conflicting results. Most found no association between 25(OH)D and risk of premenstrual

symptoms34, 178-180, while one larger study found a negative association between 25(OH)D and

symptoms of breast tenderness, fatigue, diarrhea and/or constipation, and depression181. This

negative association between 25(OH)D and premenstrual symptoms was observed in a large

prospective cohort which examined the Nurses’ Health Study II data and evaluated premenstrual

symptoms individually181. Conversely, all other observational studies examined the association

between plasma 25(OH)D and PMS, without assessing symptoms or symptom severities

individually34, 178-180. Discrepancies in the analysis of individual and grouped symptoms may

help explain these conflicting findings, as it has been previously shown that treatment response

may be specific to the premenstrual symptom182.

One clinical trial has been conducted in which adolescent patients with severe vitamin D

deficiency were supplemented with 25,000 IU biweekly vitamin D for four months and this was

found to be effective in reducing their mean premenstrual symptom severity scores as well as the

severity of all individual premenstrual symptoms studied, which included anxiety, irritability,

crying easily, and sadness183. One RCT has examined the effect of 200 mg daily vitamin D

supplementation on premenstrual symptoms in an Iranian population. Their findings showed that

after two months of supplementation symptom scores significantly decreased in the intervention

group compared to placebo for all symptoms studied, which included depression, cravings, water

retention, anxiety, and somatic changes184.

1.5 Summary and Rationale

Premenstrual symptoms are common in the North American population however their

prevalence has not been determined previously in a Canadian population. Few suitable

treatments are available for symptoms, particularly for those at mild or moderate symptom

severity. Hormonal contraceptives may be effective in treating many common symptoms, but

20

this research is inconsistent. Furthermore, it is not clear for which symptoms and severities they

are most effective. Little is also known about dietary associations with premenstrual symptoms.

Women are advised to improve diet and lifestyle, but not enough evidence exists for specific

claims. Vitamin D has been shown to be associated with the prevalence of premenstrual

symptoms in some studies, but this has not been researched in relation to the severity of

individual premenstrual symptoms.

1.6 Hypothesis and Objectives

The objectives of this dissertation were to characterize the prevalence of common

premenstrual symptoms in a Canadian population and to determine their associations with use of

hormonal contraceptives and vitamin D status. It was hypothesized that HC use and plasma

25(OH)D concentrations are inversely associated premenstrual symptom prevalence and

severity.

Chapter-specific objectives are as follows:

Objective 1: To determine the prevalence of premenstrual symptoms in a multiethnic population

and to investigate their associations with use of hormonal contraceptives.

Objective 2: To determine the associations between plasma 25-hydroxyvitamin D concentrations

and the prevalence and severity of premenstrual symptoms.

21

Chapter 2 Prevalence of Premenstrual Symptoms and Associations with

Use of Hormonal Contraceptives

22

2.1 Abstract

Background: Hormonal contraceptive (HC) use may be associated with a reduction in some

premenstrual symptoms, however, the evidence remains equivocal.

Objective: To determine the prevalence of premenstrual symptoms in a multiethnic population

of women and to investigate the association between hormonal contraceptive use and

premenstrual symptoms.

Methods: 1,048 women participating in the Toronto Nutrigenomics and Health Study provided

data on their premenstrual symptoms and HC use. Severity of symptoms was classified as none,

mild, moderate, or severe. Logistic regressions were used to calculate the relative risk (RR) and

95% confidence interval (CI) to determine the associations between HC use and duration of HC

use with premenstrual symptoms, adjusting for ethnicity and other covariates.

Results: Prevalence of individual symptoms varied, and the most commonly reported were

cramps (75%), bloating (75%), mood swings (73%), increased appetite (64%), and acne (62%).

Prevalence of cramps differed between ethnic groups (p<0.05). Use of HCs was associated with

a lower RR (95% CI) of experiencing moderate/severe: cramps (0.82, 0.72-0.93), clumsiness

(0.22, 0.07-0.73), confusion (0.22, 0.09-0.54) and desire to be alone (0.45, 0.28-0.73). HC use

was not associated with the risk of premenstrual symptoms at mild severity. HC use was not

associated with symptoms of anxiety, bloating, mood swings, increased appetite, acne, fatigue,

sexual desire, depression, nausea, headache and insomnia. Premenstrual symptoms of acne,

mood swings, bloating, increased appetite, headache, insomnia, nausea, clumsiness, and sexual

desire were not associated with HC use. Each year of HC use was associated with a decreased

RR of experience mild confusion (0.85, 0.74-0.98), and insomnia (0.77, 0.61-0.97), as well as

moderate/severe fatigue (0.89, 0.80-0.99), and mood swings (0.91, 0.85-0.98), although these did

23

not meet Benjamini-Yekutieli criteria for multiple comparisons. Other premenstrual symptoms

were not associated with duration of HC use.

Conclusion: This study demonstrates that the prevalence of some premenstrual symptoms differs

between ethnic groups and that HC use is associated with a lower risk of experiencing many, but

not all premenstrual symptoms, only at moderate/severe severity. It also suggests that duration of

HC use is not associated with the severity of premenstrual symptoms.

24

2.2 Introduction

Premenstrual symptoms include a wide range of physical, psychological and behavioral

symptoms, which occur in the late luteal phase of a woman’s reproductive cycle and subside a

few days following the onset of menses 1. Many symptoms have been described to date, and a

few most commonly experienced somatic symptoms are bloating, headache, fatigue, and muscle

cramps. Behavioural and psychological symptoms are also commonly experienced, such as

anxiety, mood swings, changes in appetite, and depression 2, 185. It is estimated that more than

80% of women regularly experience premenstrual symptoms, however, prevalence varies

between studies and populations 186-192. It is generally accepted that the prevalence is influenced

by factors such as body weight and age, however, the association with ethnicity has been

inconsistent 58, 193.

Little is known about the pathophysiology of premenstrual symptoms, and consequently,

few effective therapies have been developed for them 1. Due to the timing of the symptoms,

changes in plasma levels of progesterone and estradiol are thought to be involved in their

etiology 1. Stabilizing fluctuations of these hormones during the luteal phase with the use of

hormonal contraceptives may be effective in treating premenstrual symptoms 1, but the studies

have been inconsistent 1, 2. Furthermore, the physiological effects of HCs have previously been

shown to vary with their duration of use, such as in their effects on plasma lipid levels and VTE

risk75, 83, 84. This suggests that the effects of HCs on premenstrual symptoms may also differ with

time, although this has not been previously investigated.

Due to the large variations in frequencies of reported symptoms and their possible

associations with ethnicity and hormonal contraceptive use, the objectives of this study were to

25

determine the prevalence of various premenstrual symptoms in a multiethnic Canadian

population and to assess their associations with hormonal contraceptive use.

2.3 Methods

2.3.1 Study Population

Subjects included 1,636 men and women aged 20-29 years who participated in the

Toronto Nutrigenomics and Health (TNH) study, which is a cross-sectional examination of

young adults investigating genetics, lifestyle, and biomarkers of health 194, 195. Recruitment

occurred between 2004 and 2010. Participants completed a general health and lifestyle

questionnaire (GHLQ), a physical activity questionnaire, and a food frequency questionnaire

(FFQ). Overnight fasting blood samples were also collected for genotyping and biomarker

analysis. Exclusion criteria included current pregnancy or breastfeeding. The study protocol was

approved by the Ethics Review Board of the University of Toronto and participants provided

written informed consent.

From the initial 1,636 subjects, 520 men were excluded, 10 subjects were excluded due to

missing GHLQ information, and 4 were excluded for lack of blood samples. The remaining

1,102 subjects were categorized into four ethnic groups based on self-reported ethnic status:

Caucasian (n=514), East Asian (n=401), South Asian (n=105), or Other (n=82), as described

previously 196. Caucasians included those self-reported as European, Middle Eastern, or

Hispanic. East Asians consisted of Chinese, Japanese, Korean, Filipino, Vietnamese, Thai, and

Cambodian. South Asians included Bangladeshi, Indian, Pakistani, and Sri Lankan. The Other

category included self-reported ethnicities of Aboriginal Canadians, Afro-Caribbeans, and those

who self-reported belonging to ≥2 ethnic groups not included in the same category.

26

2.3.2 Hormonal Contraceptive Use

Hormonal contraceptive use was self-reported in the GHLQ. Subjects were categorized as

HC users (n=320) and non-users (n=782). HC users included subjects indicating current use of

HCs, regardless of HC type or delivery method (transdermal, oral, vaginal, injection, etc.). HC

users also indicated how long they have been using HCs. Subjects also reported use of any

medications in the past month. Use of anti-depressants, analgesics, or anxiolytics was considered

in the present study as ‘PMS medication use’, due to their effects on premenstrual symptoms.

2.3.3 Anthropometrics and Physical Activity

Subjects’ height and weight were measured using the protocol previously described by

Garcia-Bailo et al. (2012) 197. Subjects wore light clothing and removed their shoes during the

measurements. Body mass index (BMI) was subsequently calculated in kg/m2. Subjects self-

reported their physical activity in the GHLQ by estimating the amount of time they spent

sleeping and engaging in light, moderate, and vigorous activity. Values were then converted into

metabolic equivalent (MET) levels.

2.3.4 Premenstrual Symptoms

Premenstrual symptoms and severities were self-reported in a questionnaire included in

the GHLQ. The questionnaire included the following symptoms: cramps/skin blemish;

bloating/swelling/breast tenderness; mood swings/crying easily/irritability/angry outbursts;

increased appetite/food cravings; acne; sexual desire/activity change; fatigue;

anxiety/tension/nervousness; depression; desire to be alone; confusion/difficulty

concentrating/forgetfulness; nausea; insomnia; headache; and clumsiness. Symptom severities

were classified as none, mild, moderate, or severe. Subjects indicated the severity at which they

experienced each symptom, within the 5 days before the onset of their period and ending by the

27

4th day of their period. Subjects could also list other premenstrual symptoms experienced,

however, due to the scarcity of other symptoms they were not included in the analyses.

2.3.5 Plasma Samples and Vitamin D Measurement

Participants provided blood samples following a minimum 12-hour overnight fast.

Participants experiencing a temporary inflammatory condition (including a recent piercing or

tattoo, acupuncture, a medical or dental procedure, a vaccination or immunization, flu, an

infection, or a fever) underwent a two-week recovery period prior to providing blood samples.

Samples were collected at LifeLabs Medical Laboratory Services (Toronto, Ontario, Canada),

and 25(OH)D levels were measured at the University Health Network Specialty Lab at Toronto

General Hospital (Toronto, Ont., Canada). Plasma 25(OH)D was measured by high-performance

liquid chromatography–tandem mass spectrometry.

2.3.6 Statistical Analysis

All statistical analyses were conducted using SAS (version 9.4; SAS Institute Inc, Cary,

NC, USA). The α was set at 0.05 and all reported p-values are 2-sided. Subject characteristics

were compared between HC users and non-users by chi-square analysis for categorical variables

and t-tests for continuous variables. Distribution of continuous variables was assessed prior to

analysis and log-transformed BMI was used in all subsequent analyses. Crude mean BMI values

were reported for ease of interpretation.

The prevalence of premenstrual symptoms was defined as the frequency of subjects

experiencing the symptoms at any severity (mild, moderate, or severe). Prevalence was

calculated for each symptom in the total population, and separately for the major ethnic groups:

Caucasians (n=514), East Asians (n=401), South Asians (n=104), and Other (n=82). Logistic

regressions were used to determine differences in the prevalence of symptoms between the four

28

ethnic groups. P-values were calculated in both unadjusted models as well as adjusted models

which included the following covariates: age, BMI, HC use, physical activity, PMS medication

use and plasma 25(OH)D concentrations. Benjamini-Yekutieli adjustments for multiple

comparisons were applied (15 tests, α = 0.05: p<0.015). Differences in the prevalence of each

symptom between each pair of ethnic groups were also examined (Caucasians vs East Asians;

Caucasians vs South Asians; Caucasians vs Other; East Asians vs South Asians; East Asians vs

Other; South Asians vs Other) using logistic regressions.

Logistic regressions were used to examine the associations between HC use and

premenstrual symptom severities. The proc genmod procedure was conducted with a binomial

distribution and a log link function. Moderate and severe symptom severities were combined due

to the small number of subjects reporting severe symptoms. Relative risks (RR) and 95%

confidence intervals (CI) were reported for associations between HC use and premenstrual

symptoms. Univariate models were first used in Model 1, followed by multivariate models in

Model 2 which adjusted for ethnicity, BMI, physical activity, PMS medication use and age.

Covariates were selected based on their associations with HC use or premenstrual symptoms in

the TNH study population and previous studies. Benjamini-Yekutieli adjustments for multiple

comparisons were applied (30 tests, α = 0.05: p<0.013).

2.4 Results


Subject characteristics are reported in Table 2-1 Subject Characteristics Stratified by

Hormonal Contraceptive (HC) Use1,2. The mean age of participants was 22.6 years. HC users

were on average older (23 years) than non-users (22.4 years) (p=0.0006). HC use differed

between ethnic groups (p<0.0001), with Caucasian women reporting the greatest use of HCs

29

(43%), followed by Other (34%), South Asians (17%) and East Asians (13.0%). Reported

physical activity was greater for HC users (8.1 met-hours/week) than non-users (7.5 met-

hours/week) (p=0.003). Log-transformed BMI did not differ between HC users and non-users.

The distribution of HC types in the study population is reported in Table 2-2 Subject

Characteristics Stratified by Hormonal Contraceptive (HC) Use1,2. The most commonly used

HC brand was Tri-Cyclen (25%) followed by Alesse (22%). Yasmin, Diane35, and Marvelon

were each used by 9% of participants. Evra was used by 3% of participants, while Demulen,

Triphasel, and Triquillar were used by 1% of participants. All the aforementioned HC’s are

combinations of ethinyl estradiol and various progestins in varying doses which are administered

orally. Depo-provera, which was used by 1% of participants, is an injectable progestin-only HC

containing 150 mg medroxyprogesterone.

30

Table 2-1 Subject Characteristics Stratified by Hormonal Contraceptive (HC) Use1,2

HC Non-Users (%) HC Users (%) p-value

N

Age (years)

782

22.4±0.1

320

23.0±0.1 0.0006

Ethnicity (%) <0.0001

Caucasian 293 (57) 221 (43)

East Asian 348 (87) 53 (13)

South Asian 87 (83) 18 (17)

Other 54 (66) 28 (34)

Body mass index (kg/m2)* 22.4±0.1 22.7±0.2 0.11

Physical activity (met-h/wk) 7.5±0.1 8.1±0.2 0.003

Medication Use 205 (26) 68 (21) 0.08

Physical activity (met-h/wk) 7.5±0.1 8.2±0.2 0.003

1 Shown are crude means and standard errors of continuous variables, and n (%) of categorical variables

2 P-values were obtained using chi-square tests for categorical variables and t-tests for continuous variables.

* Indicates log-transformed variable was used for obtaining p-value

31

Table 2-2 Subject Characteristics Stratified by Hormonal Contraceptive (HC) Use1,2

HC Brand N (%) Estrogen (mg) Progestin (mg)

Tri-Cyclen1 71 (25) Ethinyl Estradiol

(0.035)

Norgestimate

(0.18 ,0.215, 0.25)

Alesse 63 (22) Ethinyl Estradiol

(0.02)

Levonorgestrel

(0.1)

Other3 41 (14) - -

Yasmin 27 (9) Ethinyl Estradiol

(0.03)

Drospirenone

(3)

Diane 35 25 (9) Ethinyl Estradiol

(0.035)

Cyproterone Acetate

(2)

Marvelon 25 (9) Ethinyl Estradiol

(0.03)

Desogestrel

(0.15)

Cyclen 13 (5) Ethinyl Estradiol

(0.035)

Norgestimate

(0.25)

Evra 9 (3) Ethinyl Estradiol

(0.02)

Norgestimate

(0.15)

Demulen 4 (1) Ethinyl Estradiol

(0.03)

Ethynodiol diacetate

(2)

Triphasel1 4 (1) Ethinyl Estradiol

(0.03, 0.04, 0.03)

Levonorgestrel

(0.05, 0.075, 0.125)

Depo-provera2 2 (1) - Medroxyprogesterone

(150)

Triquillar1 2 (1) Ethinyl Estradiol

(0.03, 0.04, 0.03)

Levonorgestrel

(0.05, 0.075, 0.125)

1 Indicates triphasic HCs, with dose of hormone reported in the order of administration 2 HC administered in the form of an intra-muscular injection every 3 months 3 Category composed of various HC formulations each used by <1% of subjects

* 3% of subjects did not report type of HC used

32

2.4.2 Prevalence of Premenstrual Symptoms

Prevalence of experiencing any premenstrual symptoms in the total population was 99%,

and did not differ significantly between ethnic groups (p=0.11). Prevalence of each premenstrual

symptom in the total population as well as stratified by ethnicity is shown in Table 2-3

Premenstrual Symptom Prevalence by Ethnicity. The most common symptoms experienced were

cramps (75%), bloating (75%), mood swings (73%), increased appetite (64%), and acne (62%).

Other premenstrual symptoms experienced were fatigue (55%), sexual desire (50%), anxiety

(37%), desire to be alone (33%), depression (29%), headache (27%), confusion (21%),

clumsiness (15%), nausea (15%), and insomnia (11%).

In the unadjusted model symptom prevalence differed between ethnic groups for

symptoms of cramps, bloating, sexual desire, headache, and confusion (p<0.05). However, after

adjustments for age, BMI, HC use, physical activity, medication use, and plasma 25(OH)D

concentrations, only the prevalence of cramps differed between ethnic groups (p<0.05). This

association met adjustments for multiple comparisons (p<0.015), where East Asians reported a

lower prevalence of cramps than Caucasians and South Asians. Prevalence of bloating, mood

swings, increased appetite, acne, fatigue, sexual desire, anxiety, desire to be alone, depression,

headache, confusion, clumsiness, nausea, and insomnia did not differ between ethnic groups in

the adjusted model.

33

Table 2-3 Premenstrual Symptom Prevalence by Ethnicity

Symptom Total (%)

N=1048

Caucasian (%)

N=46

East Asian (%)

N=395

South Asian (%)

N=100

Other (%)

N=78

Model 1

p-value

Model 2

p-value

Cramps 75 79a 67b 84a 78ab <0.0001 <0.0001

Bloating/Swelling/Breast

Tenderness 75 79 70 70 78 0.01 0.16

Mood Swings/Irritability 73 73 72 74 67 0.68 0.68

Increased Appetite/Food

Cravings 64 65 63 64 62 0.9 0.86

Acne 62 66 60 52 57 0.05 0.18

Fatigue 55 52 56 58 65 0.15 0.13

Sexual Desire/Activity Change 50 55 42 48 56 0.001 0.11

Anxiety/Tension/Nervousness 37 36 38 34 34 0.85 0.87

Desire to be alone 33 30 33 42 39 0.06 0.23

Depression 29 30 27 33 28 0.57 0.63

Headache 27 27 23 37 29 0.03 0.15

Confusion/Difficulty

Concentrating/Forgetfulness 21 18 26 24 18 0.02 0.17

Clumsiness 15 14 18 15 11 0.26 0.27

Nausea 15 16 11 20 17 0.05 0.21

Insomnia 11 9 11 16 13 0.16 0.63

34

Sorted by total premenstrual symptom prevalence. Letters indicate prevalence values which differed significantly from each other in the adjusted model (p<0.05).

35

2.4.3 Premenstrual Symptom Associations with HC use

Associations between premenstrual symptoms and HC use is shown in Table 2-4

Associations between HC Use and Premenstrual Symptom Severity and displayed graphically in

Figure 2-1 Associations between HC Use and Mild Premenstrual Symptoms and Figure 2-2

Associations between HC Use and Moderate/Severe Premenstrual Symptoms. In the unadjusted

model, HC use was associated with a lower risk of experiencing mild acne and the following

symptoms at moderate/severe severity: cramps, fatigue, anxiety, clumsiness, confusion, nausea,

depression, and desire to be alone. In Model 2, which adjusted for ethnicity, BMI, physical

activity, PMS medication use and age, HC use was not associated with any symptoms at mild

severity. HC use was associated with a lower RR (95% CI) of experiencing moderate/severe:

cramps (0.81, 0.71-0.92), anxiety (0.62, 0.41-0.93), clumsiness (0.13, 0.07-0.73), confusion

(0.22, 0.09-0.54), depression (0.55, 0.33-0.89), and desire to be alone (0.45, 0.28-0.73). All

symptoms with the exception of depression met Benjamini-Yekutieli criteria for multiple

comparisons (30 tests, α = 0.05: p<0.013). Premenstrual symptoms of bloating, mood swings,

increased appetite, acne, fatigue, sexual desire, headache, and insomnia were not associated with

HC use in Model 2. Low sample size precluded calculations of adjusted relative risks for

moderate/severe nausea, where unadjusted RRs were: 0.53 (0.25, 1.13).

Associations between duration of HC use and premenstrual symptoms severities are

reported in Table 2-5 Associations between Duration of HC Use and Premenstrual Symptoms

and displayed graphically in Figure 2-3 Associations between Duration of HC Use and Mild

Premenstrual Symptomsand Figure 2-4 Associations between Duration of HC Use and

Moderate/Severe Premenstrual Symptoms. In Model 1, duration of HC use was associated with a

decreased risk of experiencing mild insomnia and cramps. In Model 2, after adjustments for

36

ethnicity, BMI, physical activity, PMS medication use, and age, each year of HC use was

associated with a lower risk of mild cramps (0.94, 0.88-0.99), confusion (0.89, 0.79-1.00) and

insomnia (0.79, 0.64-0.98), as well as moderate/severe fatigue (0.89, 0.80-0.98). None of these

associations met Benjamini-Yekutieli criteria for multiple comparisons. Low sample size

precluded calculations of adjusted RRs for moderate/severe symptoms of confusion, insomnia,

and nausea, where unadjusted RRs were: 0.63 (0.33,1.18), 0.53 (0.16,1.82), and 0.69

(0.44,1.08), respectively.

37

Table 2-4 Associations between HC Use and Premenstrual Symptom Severity

Symptom Severity HC Non-Users

(%)

N = 782

HC Users

(%)

N = 320

Model 1

Relative Risk

Model 1

p-value

Model 2 Relative

Risk

Model 2

p-value

Acne /

Skin Blemish

None 310 (40) 111 (35) REF REF

Mild 318 (41) 161 (50) 1.17 (1.03,1.33) 0.02 1.12 (0.98,1.28) 0.10

Moderate/Severe 154 (20) 48 (15) 0.91 (0.69,1.19) 0.49 0.84 (0.63,1.12) 0.23

Bloating /

Swelling / Breast

Tenderness

None 207 (26) 71 (22) REF REF

Mild 309 (40) 143 (45) 1.12 (0.99,1.26) 0.07 1.07 (0.95,1.22) 0.27

Moderate/Severe 266 (34) 106 (33) 1.06 (0.92,1.23) 0.39 1.00 (0.86,1.16) 0.99

Cramps

None 185 (24) 89 (28) REF REF

Mild 256 (33) 128 (40) 1.02 (0.89,1.16) 0.82 0.93 (0.81,1.07) 0.29

Moderate/Severe 341 (44) 103 (32) 0.83 (0.72,0.96) 0.01 0.82 (0.71,0.93) 0.002

Mood Swings /

Crying Easily /

Irritability /Angry

Outbursts

None 212 (27) 92 (29) REF REF

Mild 287 (37) 128 (40) 1.01 (0.88,1.16) 0.87 1.02 (0.88,1.18) 0.80

Moderate/Severe 283 (36) 100 (31) 0.91 (0.78,1.06) 0.24 0.89 (0.76,1.06) 0.19

Increased

Appetite / Food

Cravings

None 282 (36) 112 (35) REF REF

Mild 232 (30) 107 (33) 1.08 (0.91,1.28) 0.35 1.06 (0.89,1.27) 0.49

Moderate/Severe 268 (34) 101 (32) 0.97 (0.82,1.15) 0.75 0.97 (0.82,1.16) 0.76

Fatigue None 342 (44) 153 (48) REF REF

Mild 245 (31) 107 (33) 0.99 (0.83,1.17) 0.87 1.00 (0.83,1.20) 0.97

38


(%)

N = 782

HC Users

(%)

N = 320

Model 1

Relative Risk

Model 1

p-value

Model 2 Relative

Risk

Model 2

p-value

Moderate/Severe 195 (25) 60 (19) 0.78 (0.61,0.99) 0.04 0.82 (0.64,1.05) 0.11

Headache

None 575 (74) 231 (72) REF REF

Mild 131 (17) 58 (18) 1.08 (0.82,1.43) 0.58 1.11 (0.84,1.49) 0.46

Moderate/Severe 76 (10) 31 (10) 1.01 (0.68,1.50) 0.95 1.01 (0.67,1.51) 0.97

Anxiety / Tension

/ Nervousness

None 480 (61) 220 (69) REF REF

Mild 201 (26) 73 (23) 0.84 (0.67,1.06) 0.15 0.88 (0.69,1.13) 0.31

Moderate/Severe 101 (13) 27 (8) 0.63 (0.42,0.94) 0.02 0.63 (0.42,0.95) 0.03

Clumsiness

None 655 (84) 278 (87) REF REF

Mild 90 (12) 39 (12) 1.02 (0.72,1.45) 0.92 1.07 (0.74,1.56) 0.71

Moderate/Severe 37 (5) 3 (1) 0.20 (0.06,0.64) 0.007 0.22 (0.07,0.73) 0.01

Confusion /

Difficulty

Concentrating /

Forgetfulness

None 599 (77) 267 (83) REF REF

Mild 121 (15) 48 (15) 0.91 (0.67,1.23) 0.53 1.00 (0.72,1.38) 1.00

Moderate/Severe 62 (8) 5 (2) 0.20 (0.08,0.48) 0.0004 0.22 (0.09,0.54) 0.001

Sexual Desire /

Activity Change

None 407 (52) 147 (46) REF REF

Mild 233 (30) 112 (35) 1.19 (1.00,1.41) 0.05 1.14 (0.95,1.37) 0.16

Moderate/Severe 142 (18) 61 (19) 1.13 (0.88,1.46) 0.33 0.96 (0.74,1.23) 0.74

Insomnia None 688 (88) 293 (92) REF REF

Mild 75 (10) 25 (8) 0.80 (0.52,1.23) 0.31 0.91 (0.57,1.43) 0.68

39


(%)

N = 782

HC Users

(%)

N = 320

Model 1

Relative Risk

Model 1

p-value

Model 2 Relative

Risk

Model 2

p-value

Moderate/Severe 19 (2) 2 (1) 0.25 (0.06,1.08) 0.06 0.23 (0.05,0.99) 0.05

Nausea*

None 664 (85) 277 (87) REF REF

Mild 81 (10) 35 (10) 1.03 (0.71,1.50) 0.87 0.95 (0.64,1.41) 0.80

Moderate/Severe 37 (5) 8 (3) 0.53 (0.25,1.13) 0.10 N/A N/A

Depression

None 543 (69) 236 (74) REF REF

Mild 150 (19) 65 (20) 1.00 (0.77,1.29) 0.99 0.96 (0.73,1.26) 0.77

Moderate/Severe 89 (11) 19 (6) 0.53 (0.33,0.85) 0.008 0.55 (0.34,0.90) 0.02

Desire to be alone

None 499 (64) 238 (75) REF REF

Mild 180 (23) 62 (19) 0.78 (0.60,1.01) 0.06 0.80 (0.62,1.04) 0.10

Moderate/Severe 103 (13) 19 (6) 0.43 (0.27,0.69) 0.0004 0.45 (0.28,0.73) 0.001

Model 1 contains unadjusted relative risks and p-values

Model 2 contains relative risks and p-values adjusted for ethnicity, log-transformed BMI, physical activity, age, and medication use

* indicates no values obtained in Model 2 due to low sample size

40

Figure 2-1 Associations between HC Use and Mild Premenstrual Symptoms

Contains relative risks and confidence intervals of experiencing each mild premenstrual symptom in HC users, adjusted for ethnicity, log-transformed BMI, physical

activity, age, and medication use

41

Figure 2-2 Associations between HC Use and Moderate/Severe Premenstrual Symptoms

Contains relative risks and confidence intervals of experiencing each moderate/severe premenstrual symptom in HC users, adjusted for ethnicity, log-transformed

BMI, physical activity, age, and medication use

42

Table 2-5 Associations between Duration of HC Use and Premenstrual Symptoms

Symptom Severity Mean

Duration of

Use (Years)1

N = 1,102

Model 1 Per

Year RR

Model 1

p-value

Model 2

Per Year RR

Model 2

p-value

Acne /

Skin Blemish

None 2.9 ± 0.2 REF REF

Mild 3.3 ± 0.2 1.03 (0.99,1.06) 0.17 1.02 (0.98,1.06) 0.36

Moderate/Severe 2.6 ± 0.3 0.95 (0.85,1.07) 0.41 0.98 (0.87,1.10) 0.70

Bloating / Swelling

/ Breast Tenderness


Mild 3.4 ± 0.2 1.02 (0.98,1.05) 0.30 1.00 (0.96,1.03) 0.91

Moderate/Severe 2.7 ± 0.3 1.00 (0.96,1.03) 0.91 0.98 (0.94,1.01) 0.22

Cramps


Mild 3.1 ± 0.2 0.93 (0.88,0.99) 0.02 0.94 (0.88,0.99) 0.03

Moderate/Severe 2.6 ± 0.2 0.97 (0.93,1.01) 0.17 0.98 (0.83,1.03) 0.45

Mood Swings /

Crying Easily /

Irritability /Angry

Outbursts


Mild 3.1 ± 0.3 0.98 (0.94,1.03) 0.47 0.96 (0.91,1.01) 0.11

Moderate/Severe 2.7 ± 0.3 0.97 (0.93,1.01) 0.17 0.94 (0.88,1.01) 0.09

Increased Appetite

/ Food Cravings


Mild 3.3 ± 0.3 1.01 (0.97,1.06) 0.58 1.01 (0.95,1.06) 0.82

Moderate/Severe 2.8 ± 0.3 0.97 (0.92,1.03) 0.32 0.98 (0.92,1.05) 0.62

Fatigue


Mild 2.9 ± 0.2 0.96 (0.90,1.02) 0.17 0.94 (0.88,1.01) 0.08

Moderate/Severe 2.7 ± 0.3 0.93 (0.85,1.02) 0.13 0.89 (0.80,0.98) 0.02

43


Duration of

Use (Years)1

N = 1,102

Model 1 Per

Year RR

Model 1

p-value

Model 2

Per Year RR

Model 2

p-value

Headache


Mild 2.8 ± 0.3 0.99 (0.90,1.08) 0.81 0.99 (0.89,1.09) 0.80

Moderate/Severe 3.0 ± 0.3 0.95 (0.83,1.09) 0.44 0.92 (0.80,1.06) 0.23

Anxiety / Tension /

Nervousness


Mild 2.8 ± 0.3 0.95 (0.88,1.03) 0.21 0.94 (0.86,1.02) 0.13

Moderate/Severe 3.0 ± 0.5 0.97 (0.85,1.11) 0.67 0.98 (0.84,1.14) 0.82

Clumsiness


Mild 2.7 ± 0.4 0.94 (0.84,1.06) 0.32 0.93 (0.82,1.06) 0.27

Moderate/Severe 3.5 ± 1.0 1.04 (0.74,1.47) 0.81 0.94 (0.66,1.33) 0.73

Confusion /

Difficulty

Concentrating /

Forgetfulness*


Mild 2.6 ± 0.4 0.92 (0.82,1.03) 0.14 0.89 (0.79,1.00) 0.05

Moderate/Severe 1.4 ± 0.9 0.63 (0.33,1.18) 0.15 N/A N/A

Sexual Desire /

Activity Change


Mild 3.0 ± 0.3 0.98 (0.93,1.03) 0.43 0.96 (0.90,1.01) 0.13

Moderate/Severe 2.8 ± 0.3 0.95 (0.87,1.04) 0.29 0.94 (0.85,1.04) 0.22

Insomnia*


Mild 1.9 ± 0.4 0.78 (0.64,0.96) 0.02 0.79 (0.64,0.98) 0.03


44


Duration of

Use (Years)1

N = 1,102

Model 1 Per

Year RR

Model 1

p-value

Model 2

Per Year RR

Model 2

p-value

Nausea*


Mild 3.3 ± 0.5 1.02 (0.91,1.14) 0.72 1.02 (0.91,1.15) 0.72


Depression


Mild 3.0 ± 0.3 0.98 (0.91,1.06) 0.62 0.97 (0.90,1.06) 0.55

Moderate/Severe 2.6 ± 0.6 0.92 (0.77,1.11) 0.38 0.93 (0.77,1.12) 0.42

Desire to be alone


Mild 2.9 ± 0.3 0.96 (0.88,1.05) 0.42 0.95 (0.86,1.04) 0.28

Moderate/Severe 2.5 ± 0.6 0.90 (0.75,1.09) 0.29 0.90 (0.70,1.09) 0.27

1 Shown are crude means ± standard errors

Model 1 contains unadjusted per-year relative risks and p-values

Model 2 contains adjusted per-year relative risks and p-values. Adjusted for ethnicity, log-transformed BMI, physical activity, age, and medication use

* indicates no values obtained in Model 2 due to low sample size

45

Figure 2-3 Associations between Duration of HC Use and Mild Premenstrual Symptoms

Contains per-year relative risks and confidence intervals of experiencing each mild premenstrual symptom with each year of HC use, adjusted for ethnicity, log-

transformed BMI, physical activity, age, and medication use

46

Figure 2-4 Associations between Duration of HC Use and Moderate/Severe Premenstrual Symptoms

Contains per-year relative risks and confidence intervals of experiencing each moderate/severe premenstrual symptom with each year of HC use, adjusted for

ethnicity, log-transformed BMI, physical activity, age, and medication use

47

2.5 Discussion

In this study, we investigated the prevalence of 15 common premenstrual symptoms and

their associations with hormonal contraceptive use in a multiethnic population of young adults

living in Canada. Our findings show that the prevalence of individual premenstrual symptoms

varies widely between the symptoms, and we observed ethnic differences in the prevalence of

several symptoms. We also found that HC use was associated with a lower risk of experiencing

several, but not all, premenstrual symptoms at moderate/severe severity. No associations were

observed between HC use and the risk of experiencing mild premenstrual symptoms. Duration of

HC use was also inversely associated with experiencing some, but not all, premenstrual

symptoms.

In our population 99% of the subjects reported experiencing premenstrual symptoms. The

same prevalence estimates were found in female university students in Thailand and Iran 190, 191.

Prevalence reported in other studies have been slightly lower and have ranged from 80% to 95%

186-189, 198. These variations in prevalence estimates may be explained by differences in symptom

assessment, subject population, and subject characteristics such as age 199. For example, the

lowest prevalence of 80% was reported in a German community survey which included

adolescent subjects aged 14-24 years 188. The inclusion of adolescents could explain the lower

prevalence, as was shown in a previous study which found that subjects under 20 or over 45

years of age had the lowest symptom prevalence, with prevalence peaking at age 35 192.

Alternatively, a survey of only married Iranian women from health clinics aged 20-45 reported a

prevalence of 86% 198. Two previous studies that included women of similar age as in the present

study reported similar prevalence for the various premenstrual symptoms 190, 191.

48

The most commonly experienced symptoms in the present study were cramps (75%),

bloating (75%), irritability (73%), increased appetite (64%), and acne (62%). These differed

from those reported in other studies, and as expected, investigations into the nature of the most

commonly experienced symptoms have yielded varying results depending on the population

studied 198, 200, 201. In a recent survey of Iranian women, the most common symptoms reported

were tiredness (70%), backache (68%), headache (59%), and insomnia (50%) 198. The most

common premenstrual symptoms reported in a population of Turkish medical students were

bloating (90%), irritability (88%), breast tenderness (83%), and anxiety (74%) 200. However, a

study involving a Mexican population demonstrated abdominal cramping to be the most

prevalent symptom (54%), while only 8% of women reported irritability 201. Discrepancies in the

prevalence of symptoms may be explained by several factors including variations in

premenstrual symptom questionnaires, BMI, age, cultural factors, and environmental exposures.

The questionnaire used in the present study differed from those used by others 198, 200, 201, which

could account for some of the variation in symptom reporting. For example, the questionnaire

used by Goker et al did not include symptoms of acne, appetite changes, or cramps which were

among the five most commonly experienced symptoms in the present population 200.

The effect of ethnicity in relation to premenstrual symptoms remains controversial.

Sternfeld et al. showed that relative to Whites, Hispanics reported a greater severity of

premenstrual symptoms whereas Asians reported a lesser severity 58. Several studies involving

US populations have shown significant differences in symptom prevalence between White and

Black women, but these racial differences were not present for all symptoms 56, 57, 202. This is in

line with the results of the present study which revealed ethnic differences in the prevalence of

some, but not all, symptoms and no ethnic differences in the total prevalence. In the present

study, many symptoms were observed to differ by ethnicity in our unadjusted models but after

49

adjustments for potential confounding variables these differences were no longer significant.

Following adjustments, ethnic differences in prevalence were observed only for cramps, which

remained significant after adjustments for multiple comparisons. East Asian participants reported

a lower prevalence of cramps compared to all other ethnic groups. Although this may reflect

differences in genetics or cultural factors that may put East Asians at lesser risk of some

premenstrual symptoms, it could also be explained by cultural differences in the interpretation

and reporting of symptoms59. Ethnic differences in premenstrual symptom reporting have been

previously observed and it was suggested that differences in the clustering of symptoms in

Chinese women compared to Western women may be a result of differences in the

conceptualization of the integration of organ systems and their relation to health and disease

influenced by Traditional Chinese Medicine59. Nonetheless, these findings may guide researchers

and healthcare practitioners in determining high-risk populations for premenstrual symptoms,

and should be supported by future large-scale studies on Canadian populations.

In the present study, hormonal contraceptive use was associated with a lower risk of

experiencing moderate/severe cramps, depression, desire to be alone, confusion, and anxiety.

Use of hormonal contraceptives was not associated with mild premenstrual symptoms. These

findings are in agreement with three previous studies that found a decrease in the overall

prevalence of symptoms as well as a decrease in the number and severity of emotional symptoms

in women using oral contraceptives 58, 95, 97. Two studies found no association between HC use

and premenstrual symptoms 98, 192. One study sampling 400 Iranian women observed a greater

prevalence of several premenstrual symptoms in HC users versus non-users 198. These studies,

however, assessed the effects of HC use on grouped symptom prevalence and severity, while the

present study identified specific premenstrual symptoms and severities which are associated with

HC use. Grouping of symptoms likely accounted for these discrepancies in findings of

50

associations between HC use and premenstrual symptoms. As shown in the present study, not all

symptoms are associated with HC use and including their prevalence likely impacted previous

findings. The present findings emphasize the importance of examining individual premenstrual

symptoms in research investigating the efficacy of treatments for PMDs. Furthermore, future

research into PMD treatment considering individual premenstrual symptom and severity will

help guide clinicians in making individualized treatment decisions for patients.

Duration of HC use was associated with a lower risk of moderate/severe fatigue and mild

cramps, confusion, and insomnia, but not after adjustments for multiple comparisons. This

suggests that our findings may have been due to chance and do not represent a true effect of

duration of use. Results from the present study should be confirmed by future analysis, as to our

knowledge, this is the first study that has examined the relationship between duration of HC use

and premenstrual symptoms. Other health outcomes have previously been associated with

duration of HC use, such as risk of VTE, lipid profiles, and cognitive outcomes75, 78, 83. The

mechanisms of these effects are not known and may be outcome-specific. The associations

observed between duration of HC use and some premenstrual symptoms in the present study do

not support any clinical recommendations as our findings did not meet the threshold for multiple

comparisons and should be confirmed in future studies.

The observed improvement of premenstrual symptoms with HC use has largely been

attributed to stabilizing ovarian sex steroid fluctuations during the reproductive cycle 43.

Treatments preventing ovulation, such as long-acting GnRH agonists and bilateral

oophorectomy, have been highly effective in diminishing premenstrual symptoms 43. HCs may

present a more favorable option for the management of premenstrual symptoms as they are

accompanied by far fewer and less severe side effects 1. Some HCs also possess anti-aldosterone

and anti-androgenic properties that likely enhance their effects on premenstrual symptoms 1, 203.

51

There is some evidence that the effect of HC use on premenstrual symptoms is dependent on the

HC formulation and regimen 86, 204. In the present study, sample size limitations precluded the

ability to study the effects of different HC formulations on premenstrual symptoms.

Interestingly, HC use is associated with a higher concentration of pro-inflammatory proteins 79

which have also been linked to an increase in the severity of some premenstrual symptoms 23, 26.

This cross-sectional examination of a young multiethnic population of Canadian women

found that 99% of women experienced some type of premenstrual symptom and that prevalence

of individual symptoms differed across ethnic groups. The present study identifies the most

common premenstrual symptoms in a Canadian population, and reports those symptoms that are

more common in some ethnic groups than in others. The findings also show that HC use was

associated with a lower risk of experiencing several premenstrual symptoms.

52

Chapter 3 Association between Plasma 25-Hydroxyvitamin D and

Premenstrual Symptoms

53

3.1 Abstract

Background: Premenstrual symptoms are experienced by up to 95% of women and little is

known about dietary risk factors. Previous studies suggest that 25(OH)D may be inversely

associated with the severity of premenstrual symptoms, but the findings have been inconclusive.

Objective: The objective of this study was to determine whether plasma 25(OH)D is associated

with premenstrual symptoms.

Methods: 1,051 women aged 20-29 years participating in the cross-sectional Toronto

Nutrigenomics and Health Study provided data on their premenstrual symptoms and fasting

blood samples were collected for plasma 25(OH)D analysis. Multinomial logistic regressions

were used to determine the association between vitamin D and the severity of individual

premenstrual symptoms. Adjustments were made for age, BMI, ethnicity, physical activity,

hormonal contraceptive use, season of blood draw, use of anxiolytics, antidepressants, or

analgesics, and calcium intake.

Results: Significant inverse associations were found between 25-hydroxyvitamin D and the

severity of premenstrual cramps, depression, and confusion (p<0.05). Only confusion met

Benjamini-Yekutieli adjustment for multiple comparisons (p<0.015). Plasma 25-hydroxyvitamin

D was not associated with any of the other premenstrual symptoms (acne, bloating, mood

swings, increased appetite, fatigue, headache, anxiety, sexual desire, insomnia, nausea,

clumsiness, or desire to be alone).

Conclusion: Our findings indicate that plasma 25-hydroxyvitamin D status is inversely

associated with some, but not all, premenstrual symptoms.

54

3.2 Introduction

Few treatments are available for premenstrual symptoms and little is known about their

risk factors, particularly when considering dietary recommendations 43. Calcium has been the

most well-studied nutrient in relation to premenstrual symptoms and there is strong evidence that

calcium supplementation may improve premenstrual symptoms9, 37, 205, 206. Similarly, low dietary

calcium intake has been shown to put women at risk of experiencing premenstrual symptoms33.

Vitamin D, which aids the absorption of calcium, has also recently been investigated for its role

in premenstrual symptoms. Evidence has suggested an association between vitamin D and

premenstrual symptoms, where those with lower vitamin D intakes experienced more severe

premenstrual symptoms 33, 178. Examinations of Nurse’s Health Study II data indicated that

consumption of an average of 400 IU of vitamin D per day was associated with a 40% decreased

risk of developing premenstrual syndrome (PMS) compared to those consuming an average of

100 IU per day. 33. This was supported by the findings of a small intervention trial showing that

administration of 25,000 IU of vitamin D for two weeks reduced the severity of premenstrual

symptoms in adolescents with severe hypovitaminosis 183.

Vitamin D status is determined by a combination of dietary vitamin D consumption and

cutaneous production, and is measured by the main circulating vitamin D metabolite 25-

hydroxyvitamin D (25(OH)D). Insufficient vitamin D status is particularly prevalent in high-

latitude countries such as Canada due to low wintertime sun exposure 207 and this may put

Canadian women at risk for increased premenstrual symptoms. Research evaluating the

association between 25(OH)D and premenstrual symptoms has been inconsistent 34, 179-181. Few

of these studies have measured the association between 25(OH)D and individual premenstrual

symptoms, and no studies have characterised these associations by symptom severity. Treatment

55

response rates have been shown to vary significantly between individual premenstrual symptoms

182, and findings from objective 1 demonstrated that associations between hormonal

contraceptives and premenstrual symptoms differed by symptom severity, suggesting that these

may be important parameters to consider. Therefore, the objective of this study was to determine

whether plasma 25(OH)D is associated with the prevalence or severity of individual


3.3 Materials and Methods


Refer to Chapter 2, section 2.3.1.

Additional exclusion criteria were applied in Study 2. From the 1,102 subjects remaining

following Study 1 exclusion criteria, 51 were excluded due to current smoking. The remaining

1,051 subjects in Study 2 were categorized into four ethnic groups based on self-reported

ethnicity: Caucasian (n=481), East Asian (n=391), South Asian (n=101), or Other (n=78).

3.3.2 Hormonal Contraceptive Use


3.3.3 Anthropometrics and Physical Activity


3.3.4 Premenstrual Symptoms


56

3.3.5 Plasma Samples and 25-Hydroxyvitamin D Analysis

Participants provided blood samples following a minimum 12-hour overnight fast.

Participants experiencing a temporary inflammatory condition (including a recent piercing or

tattoo, acupuncture, a medical or dental procedure, a vaccination or immunization, flu, an

infection, or a fever) underwent a two-week recovery period prior to providing blood samples.

Samples were collected at LifeLabs Medical Laboratory Services (Toronto, Ontario, Canada),

and 25(OH)D levels were measured at the University Health Network Specialty Lab at Toronto

General Hospital (Toronto, Ont., Canada). Plasma 25(OH)D was measured by high-performance

liquid chromatography–tandem mass spectrometry, as described previously 208. Reported plasma

25(OH)D concentrations are the sum of measured 25(OH)D3 and 25(OH)D2.

The season of blood draw was classified as follows based on month of blood draw: spring

(March, April, May), summer (June, July, August), fall (September, October, November), and

winter (December, January, February). Vitamin D status categories were created based on

recommendations from the Canadian Osteoporosis Society, the Endocrine Society, and the

Institute of Medicine163, 171, 172. Deficient vitamin D status was defined as 25(OH)D <30 nmol/L,

insufficiency was 30-49.9 nmol/L, sufficiency was 50-74.9 nmol/L, and optimal status was ≥75

nmol/L.

3.3.6 Food Frequency Questionnaire

Participants completed a 196-item Toronto-Modified Willett Food Frequency

Questionnaire (FFQ), which was used to estimate their dietary intakes of various foods,

beverages, and supplements, including calcium-containing foods and supplements. Subjects

estimated their consumption of a preassigned portion of each item over the past month by

choosing from several frequency options. Responses were then converted to estimate daily

57

averages of total calcium intake from foods and supplements. 329 participants reported currently

consuming calcium or vitamin D containing supplements.

3.3.7 Statistical Analysis

All statistical analyses were conducted using SAS (version 9.4; SAS Institute Inc, Cary,

NC, USA). The α was set at 0.05 and all reported p-values are 2-sided. Distribution of

continuous variables was assessed prior to analysis and non-normally distributed variables were

log-transformed (BMI) or square root-transformed (25(OH)D). P-values are reported from

analyses using transformed variables, while untransformed means and standard errors are

reported for ease of interpretation.

Subject characteristics were compared between subjects in four vitamin D status

categories (deficient, insufficient, sufficient, optimal) using chi-square tests for categorical

variables and ANOVA for continuous variables. Multinomial logistic regressions were used to

determine the associations between 25(OH)D and the severity of premenstrual symptoms.

Moderate and severe symptom severities were combined due to the small number of subjects

reporting severe symptoms. Univariate associations between 25(OH)D and premenstrual

symptom severities were calculated in Model 1. Multivariate models were conducted in Model 2,

which included adjustments for age, BMI, ethnicity, physical activity, season of blood draw, total

calcium intake, and use of hormonal contraceptives, anxiolytics, anti-depressants and analgesics.

Benjamini-Yekutieli adjustments for multiple comparisons were applied (15 tests, α = 0.05:

p<0.015).

3.4 Results

Subject characteristics are reported in Table 3-6 Subject Characteristics Stratified by

Vitamin D Status1,2. The distribution of vitamin D status differed between ethnic groups. The

58

majority of Caucasian (75%) and Other (51%) participants had a sufficient or optimal vitamin D

status, while only 37% of East Asian and 25% of South Asian participants had sufficient or

optimal vitamin D status. HC use was highest among those with optimal vitamin D status and

lowest in those with deficient status. Age, physical activity, and calcium intake were also highest

in those with optimal vitamin D status. BMI and use of anti-depressants, anxiolytics, or

analgesics did not significantly differ by vitamin D status.

Mean plasma 25(OH)D of subjects was 58.7 nmol/L, which represents a sufficient

vitamin D status according to criteria by the Institute of Medicine and the Canadian Osteoporosis

Society 101, 163. According to these criteria, 14% of participants had a deficient vitamin D status

(<30 nmol/L), 31% had an insufficient status (30-49.9 nmol/L), 31% had a sufficient status (50-

74.9 nmol/L), and 24% had optimal status (>75 nmol/L). Mean total calcium intake was 1,019

mg/day, which is above the Recommended Dietary Allowance (RDA) of 1000 mg/day

determined by the Canadian Osteoporosis Society for premenopausal women aged 19-50 163.

59

Table 3-6 Subject Characteristics Stratified by Vitamin D Status1,2

Deficient

n (%)

Insufficient

n (%)

Sufficient

n (%)

Optimal

n (%)

p-value

N 147 (14) 323 (31) 331 (31) 250 (24)

Age (years) 22.3 ± 0.2 22.2 ± 0.1 22.7 ± 0.1 23.1 ± 0.2 <.0001

Ethnicity <0.001

Caucasian 22 (5) 96 (20) 160 (33) 203 (42)

East Asian 69 (18) 177 (45) 117 (30) 28 (7)

South Asian 43 (43) 33 (33) 21 (21) 4 (4)

Other 13 (17) 17 (22) 33 (42) 15 (19)

HC Users 18 (12) 47 (15) 92 (28) 147 (59) <0.001

Medication Users3 37 (25) 79 (24) 68 (21) 69 (28) 0.25

BMI, (kg/m2) 22.6 ± 0.4 22.2 ± 0.2 22.6 ± 0.2 22.5 ± 0.2 0.40

Calcium, (mg/d) 788 ± 33 979 ± 28 1094 ± 26 1109 ± 31 <0.001

1 Shown are crude means ± standard errors of continuous variables, and n (%) of categorical variables. P-

values are from tests using log- transformed BMI to improve fit

2 Differences between groups were compared using chi-square tests for categorical variables and ANOVA

for continuous variables

HC: hormonal contraceptive; BMI: body mass index

60

Associations between 25(OH)D and premenstrual symptom severities are shown in Table

3-7 Associations between Plasma 25-Hydroxyvitamin D and Premenstrual Symptom Severity

and graphically in Figure 3-5 Associations between Plasma 25-Hydroxyvitamin D and

Premenstrual Symptom Severity1,2. Model 1 includes unadjusted associations and adjusted

associations are shown in Model 2. In Model 1, significant inverse associations were observed

between 25(OH)D and premenstrual symptoms of acne, cramps, clumsiness, confusion, and

desire to be alone (p<0.05). However, following adjustments for age, BMI, ethnicity, physical

activity, season of blood draw, calcium intake, and use of hormonal contraceptives, analgesics,

anxiolytics and antidepressants, only symptoms of cramps, confusion, and depression remained

significantly inversely associated with 25(OH)D concentrations (p<0.05). 25(OH)D

concentrations were significantly associated with the prevalence of confusion, where

experiencing confusion at any severity was associated with decreased 25(OH)D concentrations.

Decreased 25(OH)D concentrations were also observed in those experiencing depression at mild

severity, and moderate/severe cramps. No other symptoms were associated with 25(OH)D.

Following Benjamini-Yekutieli adjustments for multiple comparisons, only confusion remained

significantly associated with 25(OH)D (p<0.015). Results were similar within all major ethnic

groups (data not shown).

61

Table 3-7 Associations between Plasma 25-Hydroxyvitamin D and Premenstrual Symptom Severity

Symptom Severity Plasma 25(OH)D nmol/L ± SE

N = 999

Model 1 p-value

Model 2 p-value

Acne /

Skin Blemish

None 55.8 ± 1.4 0.036 0.34

Mild 60.8 ± 1.5

Moderate/Severe 59.8 ± 2.1

0.36 0.86

Bloating / Swelling /

Breast Tenderness

None 56.8 ± 1.8

Mild 58.6 ± 1.4


0.010 0.029

Cramps

None 60.3 ± 1.9a

Mild 61.2 ± 1.6a

Moderate/Severe 55.5 ± 1.4b

0.46 0.41

Mood Swings / Crying

Easily / Irritability /Angry

Outbursts

None 57.9 ± 1.7

Mild 60.2 ± 1.6


0.63 0.81

Increased Appetite / Food

Cravings

None 59.0 ± 1.5

Mild 59.6 ± 1.7


0.15 0.35

Fatigue

None 59.9 ± 1.4

Mild 59.0 ± 1.7


62


N = 999

Model 1 p-value

Model 2 p-value

0.88 0.43

Headache

None 58.5 ± 1.0

Mild 59.9 ± 2.5


0.29 0.30

Anxiety / Tension /

Nervousness

None 59.4 ± 1.1

Mild 58.5 ± 1.9


0.027 0.08

Clumsiness

None 59.4 ± 1.1

Mild 56.0 ± 2.9


<.0001 0.0037

Confusion / Difficulty

Concentrating /

Forgetfulness

None 60.5 ± 1.0a

Mild 54.4 ± 2.3b

Moderate/Severe 46.6 ± 3.4b

0.67 0.13

Sexual Desire / Activity

Change

None 58.0 ± 1.3

Mild 59.9 ± 1.7


0.10 0.41

Insomnia

None 59.4 ± 1.0

Mild 53.2 ± 2.4


0.69 0.55

63


N = 999

Model 1 p-value

Model 2 p-value

Nausea

None 59.0 ± 1.4

Mild 58.0 ± 2.7


0.12 0.046

Depression

None 59.9 ± 1.1a

Mild 56.0 ± 1.8b

Moderate/Severe 55.0 ± 3.1ab

0.007 0.31

Desire to be alone

None 60.3 ± 1.2

Mild 57.1 ± 1.8


Model 1 contains unadjusted p-values

Model 2 contains p-values adjusted for ethnicity, log-transformed BMI, physical activity, age, season of blood draw, use of anxiolytics, anti-depressants, or

analgesics, and total calcium intake.

Letters indicate means which significantly differed in Model 2

64

Figure 3-5 Associations between Plasma 25-Hydroxyvitamin D and Premenstrual Symptom Severity1,2

1Shown are mean plasma 25(OH)D concentrations and standard errors 2 P-values are adjusted for ethnicity, log-transformed BMI, physical activity, age, season of blood draw, use of anxiolytics, anti-depressants, or analgesics, and total

calcium intake. Letters indicate means which significantly differed

65

3.5 Discussion

The present cross-sectional examination of a multiethnic population of young women

investigated the association between vitamin D status and 15 common premenstrual symptoms.

Our findings show an inverse association between 25-hydroxyvitamin D and the prevalence and

severity of premenstrual cramps, depression, and confusion. These associations remained

significant after adjustments for calcium intake and other factors known to influence


The present study indicates that individual symptoms may respond differently to

25(OH)D levels and, to our knowledge, is the first study to report the association of 25(OH)D

with the prevalence and severity of individual premenstrual symptoms. Only three premenstrual

symptoms were significantly associated with 25(OH)D in the present study, and the associations

between 25(OH)D and symptom severity differed between the symptoms. 25(OH)D levels were

significantly lower in those reporting moderate/severe premenstrual cramps compared to those

reporting mild severity or no cramps. Premenstrual depression, however, may be more

responsive to vitamin D status as even participants experiencing mild depression were observed

to have significantly lower 25(OH)D. Although 25(OH)D levels were lower in those

experiencing moderate/severe depression than those with mild depression, this difference was

not significant. This may be due to the low sample size of the moderate/severe groups

contributing to their large standard errors. 25(OH)D was also inversely associated with the

prevalence of confusion at any severity.

The observed inverse association between 25(OH)D and several premenstrual symptoms

is in agreement with some 181, but not all 34, 179, 180, previous observational studies. All previous

66

studies, with the exception of one 181, examined the association of 25(OH)D with prevalence of

premenstrual syndrome (PMS), not individual premenstrual symptoms. It is important to evaluate

the effects on symptoms and symptom clusters separately, as the various somatic and affective

symptoms may have different etiologies, which could impact their association with vitamin D. A

review of the various pharmacological treatments available for PMS concluded that their

effectiveness was dependent on symptom clusters 182. For example, selective serotonin reuptake

inhibitors were found to be effective in treating mood and behavioral symptom clusters, but not

physical symptoms 182. Furthermore, the studies that did not find an association with 25(OH)D

were conducted on populations with very low 25(OH)D levels and a high rate of vitamin D

deficiency 179, 180. The population used in the present study had an approximately equal

distribution between sufficient and insufficient vitamin D statuses.

Previous examinations of data collected in the Nurse’s Health Study II have shown

inverse associations between the incidence of PMS with vitamin D intake 33 or 25(OH)D

concentrations 181. Specifically, 25(OH)D concentrations measured prior to PMS diagnosis were

inversely associated with symptoms of depression, diarrhea, fatigue, and breast ache. In the

present study, we also observed an association between 25(OH)D and premenstrual depression,

although an association with fatigue did not reach significance. Findings from the present study

should be supported by more large-scale observational studies as well as RCTs before any

clinical or public health recommendations can be made. Our findings support the analysis of

premenstrual symptoms individually in future studies, as we have shown symptom-specific

associations with plasma 25(OH)D. RCTs examining the effect of vitamin D supplements on the

severity of individual premenstrual symptom would confirm a causal relationship. Currently, two

intervention trials have been conducted which examined the effect of vitamin D supplementation

on premenstrual symptom scores183, 184. Both studies report a decrease in premenstrual symptom

67

severity scores with vitamin D supplementation183, 184, supporting the existence of a causal

relationship underlying the associations observed in the present study.

Previous examinations of data collected in the Nurse’s Health Study II have shown

inverse associations between the incidence of PMS with vitamin D intake 33 or 25(OH)D

concentrations 181. Specifically, 25(OH)D concentrations measured prior to PMS diagnosis were

inversely associated with symptoms of depression, diarrhea, fatigue, and breast ache. In the

present study, we also observed an association between 25(OH)D and premenstrual depression,

although an association with fatigue did not reach significance.

It has been suggested that premenstrual symptoms may occur as a result of calcium

dysregulation, hyperparathyroidism, and vitamin D deficiency 29, 30, 32, 37. Calcium and

1,25(OH)vitamin D have been shown to fluctuate throughout the menstrual cycle in response to

fluctuations in estradiol, with significant drops in calcium occurring in the luteal phase along

with increased metabolism of 25(OH)D into 1,25(OH)D 30, 32. Higher Vitamin D status may exert

a protective effect on premenstrual symptoms when these fluctuations occur. Findings from the

present study support this hypothesis, as the symptoms found to be associated with lower

25(OH)D levels are similar to those experienced in hypocalcemia such as depression, cramps,

forgetfulness, and impaired concentration 29. Other common symptoms of hypocalcemia such as

fatigue and anxiety 29, showed similar associations with 25(OH)D in the present study, where

25(OH)D levels decreased with increasing symptom severities. These associations did not meet

the threshold for significance in the adjusted models, perhaps due to adjustments for calcium

intake.

Vitamin D may be directly affecting premenstrual symptoms through its actions as a

neurosteroid 209, 210. 25(OH)D and 1,25(OH)D are able to cross the blood-brain barrier and

vitamin D receptors (VDRs) are distributed in areas of the brain associated with various mood

68

disorders, such as depression and seasonal affective disorder 173-175. Several epidemiological and

animal studies suggest a link between vitamin D and depression as well as anxiety 211. In keeping

with this hypothesis, the present study found 25(OH)D levels to be significantly lower in women

experiencing premenstrual depression. 25(OH)D levels were also lower in women experiencing

premenstrual anxiety and desire to be alone, although these associations did not reach

significance. These results are consistent with two recent intervention trials which observed

significant decreases in premenstrual mood symptoms, including depression and anxiety, with

administration of vitamin D supplements 183, 184.

Growing evidence indicates increased inflammation may play a role in the etiology of

premenstrual symptoms 212. This is supported by associations found between premenstrual

symptoms and increased levels of inflammatory factors such as C-reactive protein (CRP), IL-12

and interferon-gamma 23, 24, 26. Elevated CRP was found to be associated with symptoms of

anxiety and mood swings, cramps, increased appetite and bloating, and breast pain 212. Vitamin

D is involved in the modulation of immune function and inflammation 176, 177 and may reduce

premenstrual symptoms through this pathway. In the present study, no associations were found

between 25(OH)D and the premenstrual symptoms that have been associated with the

inflammation pathway including mood swings, breast pain and appetite changes. 25(OH)D was

associated with premenstrual cramps, which were shown in one study to be associated with

inflammation 26.

In summary, we found that low vitamin D status may be a risk factor for experiencing

premenstrual symptoms of cramps, depression, and confusion. No associations were observed for

many of the other premenstrual symptoms studied, suggesting there may be different

pathophysiological mechanisms underlying individual symptoms.

.

69

Chapter 4 Synopsis, Limitations and Future Directions

70

4.1 Synopsis

Few treatments are available for premenstrual symptoms which are experienced by a

majority of women. Hormonal contraceptive use may present an effective treatment option, but

more research is needed to confirm for which symptoms it is most effective. Research examining

dietary associations with premenstrual symptoms is limited. There is some preliminary evidence

that vitamin D may be associated with premenstrual symptoms, but this has not been examined

in relation to the severity of individual symptoms. The present dissertation aims to address these

gaps in knowledge.

Objective 1: To determine the prevalence of premenstrual symptoms in a multiethnic population

and to investigate their associations with use of hormonal contraceptives.

Results: Our examination of the prevalence of premenstrual symptoms in a multiethnic

Canadian population showed that premenstrual symptoms were experienced by most women and

that the prevalence of individual symptoms varied widely. Ethnicity was not associated with the

prevalence of symptoms in our population, with the exception of cramps. Hormonal

contraceptive use was associated with a reduced risk of experiencing several common

premenstrual symptoms at moderate/severe severity. HC use was not associated with

premenstrual symptoms at mild severity. Duration of HC use was associated with the risk of

experiencing mild premenstrual confusion and insomnia, as well as moderate/severe

premenstrual cramps and mood swings, although these associations did not meet adjustments for

multiple comparisons.

71

Objective 2: To determine the associations between plasma 25-hydroxyvitamin D concentrations

and the prevalence and severity of premenstrual symptoms.

Results: Plasma 25(OH)D was inversely associated with the prevalence and severity of

premenstrual cramps and confusion. 25(OH)D concentrations were also inversely associated with

a lower prevalence of depression. After adjustments for multiple comparisons, 25(OH)D was

only associated with the prevalence and severity of premenstrual confusion. Other premenstrual

symptoms were not associated with plasma 25(OH)D. These findings were replicated in all

major ethnic groups.

Our findings demonstrate that the associations of premenstrual symptoms with HC use

and 25(OH)D are symptom and severity-specific. It has been previously shown that premenstrual

symptoms may respond differently to treatments, and our results support this finding. These

findings emphasize the importance of examining associations between treatments and

premenstrual symptoms individually.

4.2 Limitations

The present study has some limitations. Firstly, the present study utilized a cross-

sectional study design, which precludes any determinations of causality or the directionality of

the associations observed and for this reason, our results should be interpreted with caution. It is

possible that mechanisms could exist whereby HC use or 25(OH)D are influenced by

premenstrual symptoms. Previous research in the field supports the associations observed in the

present study and provides support for the directionality of these relationships. Furthermore, the

large amount of information collected in the TNH study allowed for adjustments of many factors

known to influence premenstrual symptoms, minimizing the likelihood of residual confounding

72

and distinguishing between the effects of calcium and vitamin D. Of course, it is not possible for

all confounding variables to be accounted for in the present study and it is possible that observed

associations were driven by residual confounding. Although the sample size of the present study

was large, we were unable to examine the effects of various HC formulations due to sample size

constraints. The TNH study population was limited to young and educated women, so the results

of the present study can not be generalized to the overall population or other age groups. Finally,

a large number of tests were conducted in the present study and thus the results observed could

have been due to chance, although we attempted to control for this using adjustments for

multiple comparisons.

Our premenstrual symptom questionnaire was self-developed and has not been previously

validated. The questionnaire did not specify a retrospective time-frame for experiencing the

listed premenstrual symptoms, which may have resulted in an under-reporting or over-reporting

of symptoms depending on the participant’s interpretation of the question. Furthermore, the

present study relied on retrospective symptom reporting which may result in an over-reporting of

premenstrual symptoms. This may have inflated the prevalence estimates reported in the present

study, as it has been previously reported that retrospective premenstrual symptom reporting can

result in an overestimation of symptom prevalence 213. Our questionnaire was, however,

representative of common premenstrual symptoms and included questions regarding the severity

of premenstrual symptoms which allowed for unique analyses in the present study. This likely

did not impact the associations observed with HC use or 25(OH)D, as there is no evidence that

symptom over-reporting would vary by vitamin D status or between HC users and non-users.

73

4.3 Future Directions

Findings from our large cross-sectional study suggest that HC use and vitamin D are

associated with the severity of some premenstrual symptoms. However, a causal relationship can

not be determined from our data and more longitudinal research with prospective symptom

reporting is required. There is evidence that the effect of HC use on premenstrual symptoms is

dependent on the HC formulation being used. Due to sample size constraints, we were unable to

address this research question in our study. Future studies comparing the effects of different HCs

on individual premenstrual symptoms would provide useful information for clinicians and could

lead to targeted clinical approaches in the treatment of premenstrual symptoms.

Our findings suggest plasma 25(OH)D may be inversely associated with some

premenstrual symptoms. Future RCTs examining the effect of vitamin D supplementation in the

treatment of premenstrual symptoms would confirm a causal relationship and aid in the

understanding of the etiology of premenstrual symptoms. Furthermore, variation in individuals’

DBP concentrations can affect the bioavailability of 25(OH)D 214 which may impact the

relationship between vitamin D and premenstrual symptoms. Additionally, recent research

suggests that genetic variants in the vitamin D pathway, such as variants in VDR, may modify

the relationship between vitamin D and disease outcomes 215. Next steps in our research are to

examine whether common variants in VDR and DBP concentrations modify the relationship

between vitamin D and premenstrual symptoms.

74

References

1. Rapkin AJ, Akopians AL: Pathophysiology of premenstrual syndrome and premenstrual

dysphoric disorder. Menopause Int. 2012;18:52-59.

2. Braverman PK: Premenstrual syndrome and premenstrual dysphoric disorder. J Pediatr

Adolesc Gynecol. 2007;20:3-12.

3. Borenstein JE, Dean BB, Leifke E, Korner P, Yonkers KA: Differences in symptom scores

and health outcomes in premenstrual syndrome. J Womens Health (Larchmt).

2007;16:1139-1144.

4. Heinemann LA, Minh TD, Heinemann K, Lindemann M, Filonenko A: Intercountry

assessment of the impact of severe premenstrual disorders on work and daily activities.

Health Care Women Int. 2012;33:109-124.

5. Borenstein JE, Dean BB, Endicott J, et al.: Health and economic impact of the

premenstrual syndrome. J Reprod Med. 2003;48:515-524.

6. Dennerstein L, Lehert P, Heinemann K: Epidemiology of premenstrual symptoms and

disorders. Menopause Int. 2012;18:48-51.

7. Bulletins--Gynecology ACoP: ACOG Practice Bulletin: No 15: Premenstrual syndrome.

Obstet Gynecol. 2000;95:suppl 1-9.

8. Association AP: Text Revision. 4th ed. Washington, DC: American Psychiatric Association;

2000. Diagnostic and Statistical Manual of Mental Disorders.

75

9. Biggs WS, Demuth RH: Premenstrual syndrome and premenstrual dysphoric disorder.

Am Fam Physician. 2011;84:918-924.

10. Hammarback S, Ekholm UB, Backstrom T: Spontaneous anovulation causing

disappearance of cyclical symptoms in women with the premenstrual syndrome. Acta

Endocrinol (Copenh). 1991;125:132-137.

11. Schmidt PJ, Nieman LK, Danaceau MA, Adams LF, Rubinow DR: Differential behavioral

effects of gonadal steroids in women with and in those without premenstrual syndrome.

N Engl J Med. 1998;338:209-216.

12. Rupprecht R: Neuroactive steroids: mechanisms of action and

neuropsychopharmacological properties. Psychoneuroendocrinology. 2003;28:139-168.

13. Smith SS, Gong QH, Li X, et al.: Withdrawal from 3alpha-OH-5alpha-pregnan-20-One

using a pseudopregnancy model alters the kinetics of hippocampal GABAA-gated

current and increases the GABAA receptor alpha4 subunit in association with increased

anxiety. J Neurosci. 1998;18:5275-5284.

14. Wang M, Backstrom T, Sundstrom I, et al.: Neuroactive steroids and central nervous

system disorders. Int Rev Neurobiol. 2001;46:421-459.

15. Rapkin AJ, Morgan M, Goldman L, Brann DW, Simone D, Mahesh VB: Progesterone

metabolite allopregnanolone in women with premenstrual syndrome. Obstet Gynecol.

1997;90:709-714.

76

16. Rapkin AJ: The role of serotonin in premenstrual syndrome. Clin Obstet Gynecol.

1992;35:629-636.

17. McEwen BS, Parsons B: Gonadal steroid action on the brain: neurochemistry and

neuropharmacology. Annu Rev Pharmacol Toxicol. 1982;22:555-598.

18. Kato R: Serotonin content of rat brain in relation to sex and age. J Neurochem.

1960;5:202.

19. Greengrass PM, Tonge SR: Some effects of the acute and chronic administration of sex

hormones on brain monoamine concentrations. Br J Pharmacol. 1973;47:660P-661P.

20. Rapkin AJ, Edelmuth E, Chang LC, Reading AE, McGuire MT, Su TP: Whole-blood

serotonin in premenstrual syndrome. Obstet Gynecol. 1987;70:533-537.

21. Ashby CR, Jr., Carr LA, Cook CL, Steptoe MM, Franks DD: Alteration of platelet

serotonergic mechanisms and monoamine oxidase activity in premenstrual syndrome.

Biol Psychiatry. 1988;24:225-233.

22. Dimmock PW, Wyatt KM, Jones PW, O'Brien PM: Efficacy of selective serotonin-

reuptake inhibitors in premenstrual syndrome: a systematic review. Lancet.

2000;356:1131-1136.

23. Bertone-Johnson ER, Ronnenberg AG, Houghton SC, et al.: Association of inflammation

markers with menstrual symptom severity and premenstrual syndrome in young

women. Hum Reprod. 2014;29:1987-1994.

77

24. Puder JJ, Blum CA, Mueller B, De Geyter C, Dye L, Keller U: Menstrual cycle symptoms

are associated with changes in low-grade inflammation. Eur J Clin Invest. 2006;36:58-64.

25. Azizieh FY, Alyahya KO, Dingle K: Association of self-reported symptoms with serum

levels of vitamin D and multivariate cytokine profile in healthy women. J Inflamm Res.

2017;10:19-28.

26. Gold EB, Wells C, Rasor MO: The Association of Inflammation with Premenstrual

Symptoms. J Womens Health (Larchmt). 2016;25:865-874.

27. Evans J, Salamonsen LA: Inflammation, leukocytes and menstruation. Rev Endocr Metab

Disord. 2012;13:277-288.

28. Berbic M, Ng CH, Fraser IS: Inflammation and endometrial bleeding. Climacteric. 2014;17

Suppl 2:47-53.

29. Thys-Jacobs S: Micronutrients and the premenstrual syndrome: the case for calcium. J

Am Coll Nutr. 2000;19:220-227.

30. Thys-Jacobs S, McMahon D, Bilezikian JP: Cyclical changes in calcium metabolism across

the menstrual cycle in women with premenstrual dysphoric disorder. J Clin Endocrinol

Metab. 2007;92:2952-2959.

31. Chiu KM, Arnaud CD, Ju J, et al.: Correlation of estradiol, parathyroid hormone,

interleukin-6, and soluble interleukin-6 receptor during the normal menstrual cycle.

Bone. 2000;26:79-85.

78

32. Thys-Jacobs S, Alvir MJ: Calcium-regulating hormones across the menstrual cycle:

evidence of a secondary hyperparathyroidism in women with PMS. J Clin Endocrinol

Metab. 1995;80:2227-2232.

33. Bertone-Johnson ER, Hankinson SE, Bendich A, Johnson SR, Willett WC, Manson JE:

Calcium and vitamin D intake and risk of incident premenstrual syndrome. Arch Intern

Med. 2005;165:1246-1252.

34. Saeedian Kia A, Amani R, Cheraghian B: The Association between the Risk of

Premenstrual Syndrome and Vitamin D, Calcium, and Magnesium Status among

University Students: A Case Control Study. Health Promot Perspect. 2015;5:225-230.

35. Khajehei M, Abdali K, Parsanezhad ME, Tabatabaee HR: Effect of treatment with

dydrogesterone or calcium plus vitamin D on the severity of premenstrual syndrome. Int

J Gynaecol Obstet. 2009;105:158-161.

36. Ghanbari Z, Haghollahi F, Shariat M, Foroshani AR, Ashrafi M: Effects of calcium

supplement therapy in women with premenstrual syndrome. Taiwan J Obstet Gynecol.

2009;48:124-129.

37. Thys-Jacobs S, Starkey P, Bernstein D, Tian J: Calcium carbonate and the premenstrual

syndrome: effects on premenstrual and menstrual symptoms. Premenstrual Syndrome

Study Group. Am J Obstet Gynecol. 1998;179:444-452.

79

38. Thys-Jacobs S, Ceccarelli S, Bierman A, Weisman H, Cohen MA, Alvir J: Calcium

supplementation in premenstrual syndrome: a randomized crossover trial. J Gen Intern

Med. 1989;4:183-189.

39. Penland JG, Johnson PE: Dietary calcium and manganese effects on menstrual cycle

symptoms. Am J Obstet Gynecol. 1993;168:1417-1423.

40. Lee SJ, Kanis JA: An association between osteoporosis and premenstrual symptoms and

postmenopausal symptoms. Bone Miner. 1994;24:127-134.

41. SUSAN THYS-JACOBS MS, JOSE ALVIR, PATRICIA L. PADDISON, MARTA RICO, and

STANLEY J. GOLDSMITH: Reduced Bone Mass in Women With Premenstrual Syndrome.

Journal of Women's Health. 2009;4:161-168.

42. Hofmeister S, Bodden S: Premenstrual Syndrome and Premenstrual Dysphoric Disorder.

Am Fam Physician. 2016;94:236-240.

43. Yonkers KA, O'Brien PM, Eriksson E: Premenstrual syndrome. Lancet. 2008;371:1200-

1210.

44. Marjoribanks J, Brown J, O'Brien PM, Wyatt K: Selective serotonin reuptake inhibitors

for premenstrual syndrome. Cochrane Database Syst Rev. 2013:CD001396.

45. Steiner M, Pearlstein T, Cohen LS, et al.: Expert guidelines for the treatment of severe

PMS, PMDD, and comorbidities: the role of SSRIs. J Womens Health (Larchmt).

2006;15:57-69.

80

46. Wyatt KM, Dimmock PW, Ismail KM, Jones PW, O'Brien PM: The effectiveness of GnRHa

with and without 'add-back' therapy in treating premenstrual syndrome: a meta

analysis. BJOG. 2004;111:585-593.

47. Cronje WH, Vashisht A, Studd JW: Hysterectomy and bilateral oophorectomy for severe

premenstrual syndrome. Hum Reprod. 2004;19:2152-2155.

48. Deuster PA, Adera T, South-Paul J: Biological, social, and behavioral factors associated

with premenstrual syndrome. Arch Fam Med. 1999;8:122-128.

49. Choi PY, Salmon P: Symptom changes across the menstrual cycle in competitive

sportswomen, exercisers and sedentary women. Br J Clin Psychol. 1995;34 ( Pt 3):447-

460.

50. El-Lithy A, El-Mazny A, Sabbour A, El-Deeb A: Effect of aerobic exercise on premenstrual

symptoms, haematological and hormonal parameters in young women. J Obstet

Gynaecol. 2015;35:389-392.

51. Kanojia S, Sharma VK, Gandhi A, Kapoor R, Kukreja A, Subramanian SK: Effect of yoga on

autonomic functions and psychological status during both phases of menstrual cycle in

young healthy females. J Clin Diagn Res. 2013;7:2133-2139.

52. Samadi Z, Taghian F, Valiani M: The effects of 8 weeks of regular aerobic exercise on the

symptoms of premenstrual syndrome in non-athlete girls. Iran J Nurs Midwifery Res.

2013;18:14-19.

81

53. Yonkers KA, Simoni MK: Premenstrual Disorders: An Expert Review. Am J Obstet

Gynecol. 2017.

54. Bertone-Johnson ER, Hankinson SE, Willett WC, Johnson SR, Manson JE: Adiposity and

the development of premenstrual syndrome. J Womens Health (Larchmt).

2010;19:1955-1962.

55. Hashemi S, Ramezani Tehrani F, Mohammadi N, et al.: Comparison of Metabolic and

Hormonal Profiles of Women With and Without Premenstrual Syndrome: A Community

Based Cross-Sectional Study. Int J Endocrinol Metab. 2016;14:e28422.

56. Stout AL, Grady TA, Steege JF, Blazer DG, George LK, Melville ML: Premenstrual

symptoms in black and white community samples. Am J Psychiatry. 1986;143:1436-

1439.

57. Boyle CA, Berkowitz GS, Kelsey JL: Epidemiology of premenstrual symptoms. Am J Public

Health. 1987;77:349-350.

58. Sternfeld B, Swindle R, Chawla A, Long S, Kennedy S: Severity of premenstrual symptoms

in a health maintenance organization population. Obstet Gynecol. 2002;99:1014-1024.

59. Lee AM, So-Kum Tang C, Chong C: A culturally sensitive study of premenstrual and

menstrual symptoms among Chinese women. J Psychosom Obstet Gynaecol.

2009;30:105-114.

82

60. Dhont M: History of oral contraception. Eur J Contracept Reprod Health Care. 2010;15

Suppl 2:S12-18.

61. Rotermann M, Dunn S, Black A: Oral contraceptive use among women aged 15 to 49:

Results from the Canadian Health Measures Survey. Health Rep. 2015;26:21-28.

62. Rivera R, Yacobson I, Grimes D: The mechanism of action of hormonal contraceptives

and intrauterine contraceptive devices. Am J Obstet Gynecol. 1999;181:1263-1269.

63. Mishell DR, Jr., Kletzky OA, Brenner PF, Roy S, Nicoloff J: The effect of contraceptive

steroids on hypothalamic-pituitary function. Am J Obstet Gynecol. 1977;128:60-74.

64. Kastin AJ, Schally AV, Gual C, Arimura A: Release of LH and FSH after administration of

synthetic LH-releasing hormone. J Clin Endocrinol Metab. 1972;34:753-756.

65. Lobo RA, Stanczyk FZ: New knowledge in the physiology of hormonal contraceptives. Am

J Obstet Gynecol. 1994;170:1499-1507.

66. Killick S, Eyong E, Elstein M: Ovarian follicular development in oral contraceptive cycles.

Fertil Steril. 1987;48:409-413.

67. Mishell DR, Jr.: Effect of 6-alpha-methyl-17-alpha-hydroxyprogesterone on urinary

excretion of luteinizing hormone. Am J Obstet Gynecol. 1967;99:86-90.

68. Kuhl H, Jung-Hoffmann C, Wiegratz I: Gestodene-containing contraceptives. Clin Obstet

Gynecol. 1995;38:829-840.

83

69. Lammers P, Blumenthal PD, Huggins GR: Developments in contraception: a

comprehensive review of Desogen (desogestrel and ethinyl estradiol). Contraception.

1998;57:1S-27S.

70. Diczfalusy E: Probable mode of action of oral contraceptives. Res Steroids (Amst).

1966;2:389-392.

71. Mitra PK, Roychadhuri J: Effect of oral contraceptives on the ultrastructure of the

endometrium. J Gynaecol Endocrinol. 1987;3:13-15.

72. Rossmanith WG, Steffens D, Schramm G: A comparative randomized trial on the impact

of two low-dose oral contraceptives on ovarian activity, cervical permeability, and

endometrial receptivity. Contraception. 1997;56:23-30.

73. Scholes D, Hubbard RA, Ichikawa LE, et al.: Oral contraceptive use and bone density

change in adolescent and young adult women: a prospective study of age, hormone

dose, and discontinuation. J Clin Endocrinol Metab. 2011;96:E1380-1387.

74. Garcia-Bailo B, Josse AR, Jamnik J, Badawi A, El-Sohemy A: Positive association between

25-hydroxyvitamin D and C-reactive protein is confounded by hormonal contraceptive

use. J Womens Health (Larchmt). 2013;22:417-425.

75. Herings RM, Urquhart J, Leufkens HG: Venous thromboembolism among new users of

different oral contraceptives. Lancet. 1999;354:127-128.

84

76. Jick H, Kaye JA, Vasilakis-Scaramozza C, Jick SS: Risk of venous thromboembolism among

users of third generation oral contraceptives compared with users of oral contraceptives

with levonorgestrel before and after 1995: cohort and case-control analysis. BMJ.

2000;321:1190-1195.

77. Asare GA, Santa S, Ngala RA, Asiedu B, Afriyie D, Amoah AG: Effect of hormonal

contraceptives on lipid profile and the risk indices for cardiovascular disease in a

Ghanaian community. Int J Womens Health. 2014;6:597-603.

78. Egan KR, Gleason CE: Longer duration of hormonal contraceptive use predicts better

cognitive outcomes later in life. J Womens Health (Larchmt). 2012;21:1259-1266.

79. Josse AR, Garcia-Bailo B, Fischer K, El-Sohemy A: Novel effects of hormonal

contraceptive use on the plasma proteome. PLoS One. 2012;7:e45162.

80. Kuhl H: Comparative pharmacology of newer progestogens. Drugs. 1996;51:188-215.

81. Fotherby K, Caldwell AD: New progestogens in oral contraception. Contraception.

1994;49:1-32.

82. Rapkin AJ, Lewis EI: Treatment of premenstrual dysphoric disorder. Womens Health

(Lond). 2013;9:537-556.

83. Emokpae M, Uadia, PO AND Osadolor, HB: Effect of duration of use of hormonal

contraceptive pills on total lipid and lipoproteins in Nigerian women. International

Journal of Pharma and Bio Sciences. 2010;1.

85

84. Dinger JC, Heinemann LA, Kuhl-Habich D: The safety of a drospirenone-containing oral

contraceptive: final results from the European Active Surveillance Study on oral

contraceptives based on 142,475 women-years of observation. Contraception.

2007;75:344-354.

85. Lidegaard O, Lokkegaard E, Svendsen AL, Agger C: Hormonal contraception and risk of

venous thromboembolism: national follow-up study. BMJ. 2009;339:b2890.

86. Wichianpitaya J, Taneepanichskul S: A comparative efficacy of low-dose combined oral

contraceptives containing desogestrel and drospirenone in premenstrual symptoms.

Obstet Gynecol Int. 2013;2013:487143.

87. Bancroft J, Rennie D: The impact of oral contraceptives on the experience of

perimenstrual mood, clumsiness, food craving and other symptoms. J Psychosom Res.

1993;37:195-202.

88. Graham CA, Sherwin BB: A prospective treatment study of premenstrual symptoms

using a triphasic oral contraceptive. J Psychosom Res. 1992;36:257-266.

89. Halbreich U, Freeman EW, Rapkin AJ, et al.: Continuous oral levonorgestrel/ethinyl

estradiol for treating premenstrual dysphoric disorder. Contraception. 2012;85:19-27.

90. Marr J, Niknian M, Shulman LP, Lynen R: Premenstrual dysphoric disorder symptom

cluster improvement by cycle with the combined oral contraceptive ethinylestradiol 20

mcg plus drospirenone 3 mg administered in a 24/4 regimen. Contraception.

2011;84:81-86.

86

91. Thong JF, Lo S, Houghton R, Moore-Gillon V: A prospective comparative study to

examine the effects of oral diazepam on blood pressure and anxiety levels in patients

with acute epistaxis. J Laryngol Otol. 2007;121:124-129.

92. Barbosa IC, Filho CI, Faggion D, Jr., Baracat EC: Prospective, open-label, noncomparative

study to assess cycle control, safety and acceptability of a new oral contraceptive

containing gestodene 60 microg and ethinylestradiol 15 microg (Minesse).

Contraception. 2006;73:30-33.

93. Taneepanichskul S, Jaisamrarn U, Phupong V: Efficacy of Yasmin in premenstrual

symptoms. Arch Gynecol Obstet. 2007;275:433-438.

94. Witjes H, Creinin MD, Sundstrom-Poromaa I, Martin Nguyen A, Korver T: Comparative

analysis of the effects of nomegestrol acetate/17 beta-estradiol and

drospirenone/ethinylestradiol on premenstrual and menstrual symptoms and

dysmenorrhea. Eur J Contracept Reprod Health Care. 2015;20:296-307.

95. Sadler C, Smith H, Hammond J, et al.: Lifestyle factors, hormonal contraception, and

premenstrual symptoms: the United Kingdom Southampton Women's Survey. J

Womens Health (Larchmt). 2010;19:391-396.

96. Gold EB, Bair Y, Block G, et al.: Diet and lifestyle factors associated with premenstrual

symptoms in a racially diverse community sample: Study of Women's Health Across the

Nation (SWAN). J Womens Health (Larchmt). 2007;16:641-656.

87

97. Potter J, Bouyer J, Trussell J, Moreau C: Premenstrual syndrome prevalence and

fluctuation over time: results from a French population-based survey. J Womens Health

(Larchmt). 2009;18:31-39.

98. Joffe H, Cohen LS, Harlow BL: Impact of oral contraceptive pill use on premenstrual

mood: predictors of improvement and deterioration. Am J Obstet Gynecol.

2003;189:1523-1530.

99. Bakhshani NM, Hosseinbor M, Shahraki Z, Sakhavar N: Premenstrual syndrome

symptomatology among married women of fertile age based on methods of

contraception (hormonal versus non-hormonal methods of contraception). Glob J

Health Sci. 2013;6:105-111.

100. Garcia-Bailo B, Jamnik J, Da Costa LA, Borchers CH, Badawi A, El-Sohemy A: Plasma 25-

hydroxyvitamin D, hormonal contraceptive use, and the plasma proteome in Caucasian,

East Asian, and South Asian young adults. J Proteome Res. 2013;12:1797-1807.

101. Hanley DA, Cranney A, Jones G, et al.: Vitamin D in adult health and disease: a review

and guideline statement from Osteoporosis Canada. CMAJ. 2010;182:E610-618.

102. Norman AW: From vitamin D to hormone D: fundamentals of the vitamin D endocrine

system essential for good health. Am J Clin Nutr. 2008;88:491S-499S.

103. Holick MF: Vitamin D: evolutionary, physiological and health perspectives. Curr Drug

Targets. 2011;12:4-18.

88

104. Freedman DM, Looker AC, Chang SC, Graubard BI: Prospective study of serum vitamin D

and cancer mortality in the United States. J Natl Cancer Inst. 2007;99:1594-1602.

105. Janz T PC: Vitamin D blood levels of Canadians. Ottawa (Canada): Statistics Canada.

2013.

106. Holden JM, Lemar LE, Exler J: Vitamin D in foods: development of the US Department of

Agriculture database. Am J Clin Nutr. 2008;87:1092S-1096S.

107. Reboul E, Borel P: Proteins involved in uptake, intracellular transport and basolateral

secretion of fat-soluble vitamins and carotenoids by mammalian enterocytes. Prog Lipid

Res. 2011;50:388-402.

108. Sawada N, Sakaki T, Ohta M, Inouye K: Metabolism of vitamin D(3) by human CYP27A1.

Biochem Biophys Res Commun. 2000;273:977-984.

109. Clements MR, Davies M, Hayes ME, et al.: The role of 1,25-dihydroxyvitamin D in the

mechanism of acquired vitamin D deficiency. Clin Endocrinol (Oxf). 1992;37:17-27.

110. Prosser DE, Jones G: Enzymes involved in the activation and inactivation of vitamin D.

Trends Biochem Sci. 2004;29:664-673.

111. Haussler MR, Jurutka PW, Mizwicki M, Norman AW: Vitamin D receptor (VDR)-mediated

actions of 1alpha,25(OH)(2)vitamin D(3): genomic and non-genomic mechanisms. Best

Pract Res Clin Endocrinol Metab. 2011;25:543-559.

89

112. Wootton AM: Improving the measurement of 25-hydroxyvitamin D. Clin Biochem Rev.

2005;26:33-36.

113. Wacker M, Holick MF: Vitamin D - effects on skeletal and extraskeletal health and the

need for supplementation. Nutrients. 2013;5:111-148.

114. Christakos S, Dhawan P, Liu Y, Peng X, Porta A: New insights into the mechanisms of

vitamin D action. J Cell Biochem. 2003;88:695-705.

115. Stoffels K, Overbergh L, Giulietti A, Verlinden L, Bouillon R, Mathieu C: Immune

regulation of 25-hydroxyvitamin-D3-1alpha-hydroxylase in human monocytes. J Bone

Miner Res. 2006;21:37-47.

116. Zehnder D, Bland R, Williams MC, et al.: Extrarenal expression of 25-hydroxyvitamin

d(3)-1 alpha-hydroxylase. J Clin Endocrinol Metab. 2001;86:888-894.

117. Nair R, Maseeh A: Vitamin D: The "sunshine" vitamin. J Pharmacol Pharmacother.

2012;3:118-126.

118. van Driel M, Koedam M, Buurman CJ, et al.: Evidence that both 1alpha,25-

dihydroxyvitamin D3 and 24-hydroxylated D3 enhance human osteoblast differentiation

and mineralization. J Cell Biochem. 2006;99:922-935.

119. Piek E, Sleumer LS, van Someren EP, et al.: Osteo-transcriptomics of human

mesenchymal stem cells: accelerated gene expression and osteoblast differentiation

90

induced by vitamin D reveals c-MYC as an enhancer of BMP2-induced osteogenesis.

Bone. 2010;46:613-627.

120. Ducy P, Zhang R, Geoffroy V, Ridall AL, Karsenty G: Osf2/Cbfa1: a transcriptional

activator of osteoblast differentiation. Cell. 1997;89:747-754.

121. Bischoff HA, Stahelin HB, Dick W, et al.: Effects of vitamin D and calcium

supplementation on falls: a randomized controlled trial. J Bone Miner Res. 2003;18:343-

351.

122. Bischoff-Ferrari HA, Dawson-Hughes B, Willett WC, et al.: Effect of Vitamin D on falls: a

meta-analysis. JAMA. 2004;291:1999-2006.

123. Bischoff-Ferrari HA, Dietrich T, Orav EJ, et al.: Higher 25-hydroxyvitamin D

concentrations are associated with better lower-extremity function in both active and

inactive persons aged > or =60 y. Am J Clin Nutr. 2004;80:752-758.

124. Agergaard J, Trostrup J, Uth J, et al.: Does vitamin-D intake during resistance training

improve the skeletal muscle hypertrophic and strength response in young and elderly

men? - a randomized controlled trial. Nutr Metab (Lond). 2015;12:32.

125. Bouillon R, Verstuyf A: Vitamin D, mitochondria, and muscle. J Clin Endocrinol Metab.

2013;98:961-963.

91

126. Tieland M, Brouwer-Brolsma EM, Nienaber-Rousseau C, van Loon LJ, De Groot LC: Low

vitamin D status is associated with reduced muscle mass and impaired physical

performance in frail elderly people. Eur J Clin Nutr. 2013;67:1050-1055.

127. Scragg R, Sowers M, Bell C: Serum 25-hydroxyvitamin D, ethnicity, and blood pressure in

the Third National Health and Nutrition Examination Survey. Am J Hypertens.

2007;20:713-719.

128. Hintzpeter B, Mensink GB, Thierfelder W, Muller MJ, Scheidt-Nave C: Vitamin D status

and health correlates among German adults. Eur J Clin Nutr. 2008;62:1079-1089.

129. Hypponen E, Boucher BJ, Berry DJ, Power C: 25-hydroxyvitamin D, IGF-1, and metabolic

syndrome at 45 years of age: a cross-sectional study in the 1958 British Birth Cohort.

Diabetes. 2008;57:298-305.

130. Wang TJ, Pencina MJ, Booth SL, et al.: Vitamin D deficiency and risk of cardiovascular

disease. Circulation. 2008;117:503-511.

131. Pilz S, Tomaschitz A, Ritz E, Pieber TR: Vitamin D status and arterial hypertension: a

systematic review. Nat Rev Cardiol. 2009;6:621-630.

132. Cippitelli M, Santoni A: Vitamin D3: a transcriptional modulator of the interferon-gamma

gene. Eur J Immunol. 1998;28:3017-3030.

92

133. Boonstra A, Barrat FJ, Crain C, Heath VL, Savelkoul HF, O'Garra A: 1alpha,25-

Dihydroxyvitamin d3 has a direct effect on naive CD4(+) T cells to enhance the

development of Th2 cells. J Immunol. 2001;167:4974-4980.

134. Codoner-Franch P, Tavarez-Alonso S, Simo-Jorda R, Laporta-Martin P, Carratala-Calvo A,

Alonso-Iglesias E: Vitamin D status is linked to biomarkers of oxidative stress,

inflammation, and endothelial activation in obese children. J Pediatr. 2012;161:848-854.

135. Salekzamani S, Neyestani TR, Alavi-Majd H, et al.: Is vitamin D status a determining

factor for metabolic syndrome? A case-control study. Diabetes Metab Syndr Obes.

2011;4:205-212.

136. Kim M, Na W, Sohn C: Correlation between vitamin D and cardiovascular disease

predictors in overweight and obese Koreans. J Clin Biochem Nutr. 2013;52:167-171.

137. Jorde R, Sneve M, Torjesen PA, Figenschau Y, Goransson LG, Omdal R: No effect of

supplementation with cholecalciferol on cytokines and markers of inflammation in

overweight and obese subjects. Cytokine. 2010;50:175-180.

138. Barnes MS, Horigan G, Cashman KD, et al.: Maintenance of wintertime vitamin D status

with cholecalciferol supplementation is not associated with alterations in serum

cytokine concentrations among apparently healthy younger or older adults. J Nutr.

2011;141:476-481.

139. Llewellyn DJ, Lang IA, Langa KM, et al.: Vitamin D and risk of cognitive decline in elderly

persons. Arch Intern Med. 2010;170:1135-1141.

93

140. Jorde R, Sneve M, Figenschau Y, Svartberg J, Waterloo K: Effects of vitamin D

supplementation on symptoms of depression in overweight and obese subjects:

randomized double blind trial. J Intern Med. 2008;264:599-609.

141. Matsuoka LY, Wortsman J, Hollis BW: Use of topical sunscreen for the evaluation of

regional synthesis of vitamin D3. J Am Acad Dermatol. 1990;22:772-775.

142. Webb AR, Kline L, Holick MF: Influence of season and latitude on the cutaneous

synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not

promote vitamin D3 synthesis in human skin. J Clin Endocrinol Metab. 1988;67:373-378.

143. Clemens TL, Adams JS, Henderson SL, Holick MF: Increased skin pigment reduces the

capacity of skin to synthesise vitamin D3. Lancet. 1982;1:74-76.

144. Prentice A: Vitamin D deficiency: a global perspective. Nutr Rev. 2008;66:S153-164.

145. Norman AW: Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D:

integral components of the vitamin D endocrine system. Am J Clin Nutr. 1998;67:1108-

1110.

146. Wu H, Gozdzik A, Barta JL, et al.: The development and evaluation of a food frequency

questionnaire used in assessing vitamin D intake in a sample of healthy young Canadian

adults of diverse ancestry. Nutr Res. 2009;29:255-261.

147. Aasheim ET, Hofso D, Hjelmesaeth J, Birkeland KI, Bohmer T: Vitamin status in morbidly

obese patients: a cross-sectional study. Am J Clin Nutr. 2008;87:362-369.

94

148. Cheng S, Massaro JM, Fox CS, et al.: Adiposity, cardiometabolic risk, and vitamin D

status: the Framingham Heart Study. Diabetes. 2010;59:242-248.

149. Earthman CP, Beckman LM, Masodkar K, Sibley SD: The link between obesity and low

circulating 25-hydroxyvitamin D concentrations: considerations and implications. Int J

Obes (Lond). 2012;36:387-396.

150. Blum M, Dolnikowski G, Seyoum E, et al.: Vitamin D(3) in fat tissue. Endocrine.

2008;33:90-94.

151. Harris SS, Dawson-Hughes B: The association of oral contraceptive use with plasma 25-

hydroxyvitamin D levels. J Am Coll Nutr. 1998;17:282-284.

152. Sowers MR, Wallace RB, Hollis BW, Lemke JH: Parameters related to 25-OH-D levels in a

population-based study of women. Am J Clin Nutr. 1986;43:621-628.

153. Aarskog D, Aksnes L, Markestad T, Rodland O: Effect of estrogen on vitamin D

metabolism in tall girls. J Clin Endocrinol Metab. 1983;57:1155-1158.

154. Lechner D, Bajna E, Adlercreutz H, Cross HS: Genistein and 17beta-estradiol, but not

equol, regulate vitamin D synthesis in human colon and breast cancer cells. Anticancer

Res. 2006;26:2597-2603.

155. Tanaka Y, Castillo L, DeLuca HF: Control of renal vitamin D hydroxylases in birds by sex

hormones. Proc Natl Acad Sci U S A. 1976;73:2701-2705.

95

156. van Hoof HJ, de Sevaux RG, van Baelen H, et al.: Relationship between free and total

1,25-dihydroxyvitamin D in conditions of modified binding. Eur J Endocrinol.

2001;144:391-396.

157. Hypponen E, Berry DJ, Wjst M, Power C: Serum 25-hydroxyvitamin D and IgE - a

significant but nonlinear relationship. Allergy. 2009;64:613-620.

158. Cooper JD, Smyth DJ, Walker NM, et al.: Inherited variation in vitamin D genes is

associated with predisposition to autoimmune disease type 1 diabetes. Diabetes.

2011;60:1624-1631.

159. d'Alesio A, Garabedian M, Sabatier JP, et al.: Two single-nucleotide polymorphisms in

the human vitamin D receptor promoter change protein-DNA complex formation and

are associated with height and vitamin D status in adolescent girls. Hum Mol Genet.

2005;14:3539-3548.

160. Hunter D, De Lange M, Snieder H, et al.: Genetic contribution to bone metabolism,

calcium excretion, and vitamin D and parathyroid hormone regulation. J Bone Miner Res.

2001;16:371-378.

161. Karohl C, Su S, Kumari M, et al.: Heritability and seasonal variability of vitamin D

concentrations in male twins. Am J Clin Nutr. 2010;92:1393-1398.

162. Orton SM, Morris AP, Herrera BM, et al.: Evidence for genetic regulation of vitamin D

status in twins with multiple sclerosis. Am J Clin Nutr. 2008;88:441-447.

96

163. . In: Ross AC, Taylor CL, Yaktine AL, Del Valle HB, eds. Dietary Reference Intakes for

Calcium and Vitamin D. Washington (DC)2011.

164. Bikle DD, Gee E, Halloran B, Kowalski MA, Ryzen E, Haddad JG: Assessment of the free

fraction of 25-hydroxyvitamin D in serum and its regulation by albumin and the vitamin

D-binding protein. J Clin Endocrinol Metab. 1986;63:954-959.

165. Hollis BW: Editorial: The determination of circulating 25-hydroxyvitamin D: no easy task.

J Clin Endocrinol Metab. 2004;89:3149-3151.

166. Roth HJ, Schmidt-Gayk H, Weber H, Niederau C: Accuracy and clinical implications of

seven 25-hydroxyvitamin D methods compared with liquid chromatography-tandem

mass spectrometry as a reference. Ann Clin Biochem. 2008;45:153-159.

167. Snellman G, Melhus H, Gedeborg R, et al.: Determining vitamin D status: a comparison

between commercially available assays. PLoS One. 2010;5:e11555.

168. Maxmen A: Nutrition advice: the vitamin D-lemma. Nature. 2011;475:23-25.

169. Schwalfenberg GK, Whiting SJ: A Canadian response to the 2010 Institute of Medicine

vitamin D and calcium guidelines. Public Health Nutr. 2011;14:746-748.

170. Vieth R: Why the minimum desirable serum 25-hydroxyvitamin D level should be 75

nmol/L (30 ng/ml). Best Pract Res Clin Endocrinol Metab. 2011;25:681-691.

97

171. Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B: Estimation

of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes.

Am J Clin Nutr. 2006;84:18-28.

172. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al.: Evaluation, treatment, and prevention

of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol

Metab. 2011;96:1911-1930.

173. Eyles DW, Smith S, Kinobe R, Hewison M, McGrath JJ: Distribution of the vitamin D

receptor and 1 alpha-hydroxylase in human brain. J Chem Neuroanat. 2005;29:21-30.

174. Bertone-Johnson ER: Vitamin D and the occurrence of depression: causal association or

circumstantial evidence? Nutr Rev. 2009;67:481-492.

175. Stumpf WE, Privette TH: Light, vitamin D and psychiatry. Role of 1,25 dihydroxyvitamin

D3 (soltriol) in etiology and therapy of seasonal affective disorder and other mental

processes. Psychopharmacology (Berl). 1989;97:285-294.

176. Bouillon R, Carmeliet G, Verlinden L, et al.: Vitamin D and human health: lessons from

vitamin D receptor null mice. Endocr Rev. 2008;29:726-776.

177. Lagishetty V, Liu NQ, Hewison M: Vitamin D metabolism and innate immunity. Mol Cell

Endocrinol. 2011;347:97-105.

98

178. Bertone-Johnson ER, Chocano-Bedoya PO, Zagarins SE, Micka AE, Ronnenberg AG:

Dietary vitamin D intake, 25-hydroxyvitamin D3 levels and premenstrual syndrome in a

college-aged population. J Steroid Biochem Mol Biol. 2010;121:434-437.

179. Obeidat BA, Alchalabi HA, Abdul-Razzak KK, Al-Farras MI: Premenstrual symptoms in

dysmenorrheic college students: prevalence and relation to vitamin D and parathyroid

hormone levels. Int J Environ Res Public Health. 2012;9:4210-4222.

180. Rajaei S, Akbari Sene A, Norouzi S, et al.: The relationship between serum vitamin D

level and premenstrual syndrome in Iranian women. Int J Reprod Biomed (Yazd).

2016;14:665-668.

181. Bertone-Johnson ER, Hankinson SE, Forger NG, et al.: Plasma 25-hydroxyvitamin D and

risk of premenstrual syndrome in a prospective cohort study. BMC Womens Health.

2014;14:56.

182. Halbreich U, O'Brien PM, Eriksson E, Backstrom T, Yonkers KA, Freeman EW: Are there

differential symptom profiles that improve in response to different pharmacological

treatments of premenstrual syndrome/premenstrual dysphoric disorder? CNS Drugs.

2006;20:523-547.

183. Tartagni M, Cicinelli MV, Tartagni MV, et al.: Vitamin D Supplementation for

Premenstrual Syndrome-Related Mood Disorders in Adolescents with Severe

Hypovitaminosis D. J Pediatr Adolesc Gynecol. 2016;29:357-361.

99

184. Dadkhah H, Ebrahimi E, Fathizadeh N: Evaluating the effects of vitamin D and vitamin E

supplement on premenstrual syndrome: A randomized, double-blind, controlled trial.

Iran J Nurs Midwifery Res. 2016;21:159-164.

185. Halbreich U: The diagnosis of premenstrual syndromes and premenstrual dysphoric

disorder--clinical procedures and research perspectives. Gynecol Endocrinol.

2004;19:320-334.

186. Tschudin S, Bertea PC, Zemp E: Prevalence and predictors of premenstrual syndrome

and premenstrual dysphoric disorder in a population-based sample. Arch Womens Ment

Health. 2010;13:485-494.

187. Tolossa FW, Bekele ML: Prevalence, impacts and medical managements of premenstrual

syndrome among female students: cross-sectional study in College of Health Sciences,

Mekelle University, Mekelle, northern Ethiopia. BMC Womens Health. 2014;14:52.

188. Wittchen HU, Becker E, Lieb R, Krause P: Prevalence, incidence and stability of

premenstrual dysphoric disorder in the community. Psychol Med. 2002;32:119-132.

189. Takeda T, Tasaka K, Sakata M, Murata Y: Prevalence of premenstrual syndrome and

premenstrual dysphoric disorder in Japanese women. Arch Womens Ment Health.

2006;9:209-212.

190. Thu MD, O.G Sawhsarkapaw: Premenstrual Syndrome among Female University

Students in Thailand. AU J.T. 2006;9:158-162.

100

191. Bakhshani NM, Mousavi MN, Khodabandeh G: Prevalence and severity of premenstrual

symptoms among Iranian female university students. J Pak Med Assoc. 2009;59:205-

208.

192. Dennerstein L, Lehert P, Backstrom TC, Heinemann K: Premenstrual symptoms --

severity, duration and typology: an international cross-sectional study. Menopause Int.

2009;15:120-126.

193. Adewuya AO, Loto OM, Adewumi TA: Pattern and correlates of premenstrual

symptomatology amongst Nigerian University students. J Psychosom Obstet Gynaecol.

2009;30:127-132.

194. Garcia-Bailo B, Jamnik J, Da Costa LA, Badawi A, El-Sohemy A: Genetic variation in the

vitamin D receptor, plasma 25-hydroxyvitamin D, and biomarkers of cardiometabolic

disease in Caucasian young adults. J Nutrigenet Nutrigenomics. 2013;6:256-267.

195. Cahill LE, El-Sohemy A: Haptoglobin genotype modifies the association between dietary

vitamin C and serum ascorbic acid deficiency. Am J Clin Nutr. 2010;92:1494-1500.

196. Brenner DR, Boucher BA, Kreiger N, Jenkins D, El-Sohemy A: Dietary patterns in an

ethnoculturally diverse population of young Canadian adults. Can J Diet Pract Res.

2011;72:e161-168.

197. Garcia-Bailo B, Brenner DR, Nielsen D, et al.: Dietary patterns and ethnicity are

associated with distinct plasma proteomic groups. Am J Clin Nutr. 2012;95:352-361.

101

198. Bakhshani NM, Hosseinbor M, Shahraki Z, Sakhavar N: Premenstrual syndrome

symptomatology among married women of fertile age based on methods of

contraception (hormonal versus non-hormonal methods of contraception). Glob J

Health Sci. 2014;6:105-111.

199. Dennerstein L, Lehert P, Keung LS, Pal SA, Choi D: A population-based survey of Asian

women's experience of premenstrual symptoms. Menopause Int. 2010;16:139-145.

200. Goker A, Artunc-Ulkumen B, Aktenk F, Ikiz N: Premenstrual syndrome in Turkish medical

students and their quality of life. J Obstet Gynaecol. 2015;35:275-278.

201. Sievert LL, Bertone-Johnson E: Perimenstrual symptoms and symptoms at midlife in

Puebla, Mexico. Climacteric. 2013;16:169-178.

202. Woods NF, Most A, Dery GK: Prevalene of perimenstrual symptoms. Am J Public Health.

1982;72:1257-1264.

203. Kelderhouse K, Taylor JS: A review of treatment and management modalities for

premenstrual dysphoric disorder. Nurs Womens Health. 2013;17:294-305.

204. Legro RS, Pauli JG, Kunselman AR, et al.: Effects of continuous versus cyclical oral

contraception: a randomized controlled trial. J Clin Endocrinol Metab. 2008;93:420-429.

205. Shobeiri F, Araste FE, Ebrahimi R, Jenabi E, Nazari M: Effect of calcium on premenstrual

syndrome: A double-blind randomized clinical trial. Obstet Gynecol Sci. 2017;60:100-

105.

102

206. Shehata NA: Calcium versus oral contraceptive pills containing drospirenone for the

treatment of mild to moderate premenstrual syndrome: a double blind randomized

placebo controlled trial. Eur J Obstet Gynecol Reprod Biol. 2016;198:100-104.

207. Rucker D, Allan JA, Fick GH, Hanley DA: Vitamin D insufficiency in a population of healthy

western Canadians. CMAJ. 2002;166:1517-1524.

208. Garcia-Bailo B, Karmali M, Badawi A, El-Sohemy A: Plasma 25-hydroxyvitamin D,

hormonal contraceptive use, and cardiometabolic disease risk in an ethnically diverse

population of young adults. J Am Coll Nutr. 2013;32:296-306.

209. Stewart A, Wong K, Cachat J, et al.: Neurosteroid vitamin D system as a nontraditional

drug target in neuropsychopharmacology. Behav Pharmacol. 2010;21:420-426.

210. Groves NJ, McGrath JJ, Burne TH: Vitamin D as a neurosteroid affecting the developing

and adult brain. Annu Rev Nutr. 2014;34:117-141.

211. Hoogendijk WJ, Lips P, Dik MG, Deeg DJ, Beekman AT, Penninx BW: Depression is

associated with decreased 25-hydroxyvitamin D and increased parathyroid hormone

levels in older adults. Arch Gen Psychiatry. 2008;65:508-512.

212. Bertone-Johnson ER: Chronic Inflammation and Premenstrual Syndrome: A Missing Link

Found? J Womens Health (Larchmt). 2016;25:857-858.

103

213. Marvan ML, Cortes-Iniestra S: Women's beliefs about the prevalence of premenstrual

syndrome and biases in recall of premenstrual changes. Health Psychol. 2001;20:276-

280.

214. Powe CE, Evans MK, Wenger J, et al.: Vitamin D-binding protein and vitamin D status of

black Americans and white Americans. N Engl J Med. 2013;369:1991-2000.

215. Levin GP, Robinson-Cohen C, de Boer IH, et al.: Genetic variants and associations of 25-

hydroxyvitamin D concentrations with major clinical outcomes. JAMA. 2012;308:1898-

1905.

104

Appendices

Table A-1 GHLQ Premenstrual Symptom Questionnaire

Date post:	03-Jun-2020
Category:	Documents
Upload:	others
View:	3 times
Download:	0 times

Associations between Plasma 25-Hydroxyvitamin D, Hormonal ... · Associations between Plasma...

Documents