HUN 3403 Wk2 D1b

Chapter 6 Nutrition During Lactation

Introduction

• Information beneficial to health care professionals to promote breastfeeding is included:– Benefits of breastfeeding– Lactation physiology– Human milk composition – How to breastfeed an infant– Maternal dietary needs– Breastfeeding promotion, facilitation, & support

Lactation Physiology

• Mammary gland– Source of milk for offspring, the breast

• Alveoli– Rounded or oblong shaped cavity present in breast

• Secretory cells– Cells in acinus (milk gland) that are responsible for

secreting milk components into ducts

• Myoepithelial cells– Line the alveoli & can contract to cause milk to be

secreted into ducts

Lactation Physiology

• Oxytocin– Hormone produced during letdown that causes milk to

eject into ducts

• Lobes – Rounded structures of mammary glands

• Lactogenesis– Term for human milk production

• Prolactin– A hormone necessary for milk production

Breast of a Lactating Female

Functional Units of the Mammary Glands

– Alveoli in mammary glands are the functional units

– Each is composed of secretory cells with a duct in the center

– Myoepithelial cells, that line the alveoli, contract during letdown causing milk ejection

Mammary Gland Development

• During puberty, the ovaries mature with increases in estrogen & progesterone

• Hormones impacting lactation and their functions are in Table 6.1

• Primary hormones contributing to breast development and lactation are:– Estrogen —Progesterone– Human growth hormone —Prolactin– Human placental lactogen —Oxytocin

Mammary Gland Development

Mammary Gland Development

• Estrogen & progesterone increase during puberty

• Levels of both hormones increase dramatically to prepare mammary glands for lactation

Stages of Lactogenesis

• Lactogenesis I (birth to 2-5 days) milk formation begins

• Lactogenesis II—(begins 2-5 days after birth) increased blood flow to breast; milk “comes in”

• Lactogenesis III—(begins at ~10 day after birth) milk composition is stable

Hormonal Control of Lactation

• Prolactin– Stimulates milk production – Released in response to suckling, stress, sleep, &

sexual intercourse

• Oxytocin– Stimulates letdown– Tingling of the breast may occur corresponding to

contractions in milk duct– Causes uterus to contract, seal blood vessels, &

shrink in size

The Letdown Reflex

Human Milk Composition

• Human milk is the only food needed by the majority of healthy infants for ~ 6 months– It nurtures & protects infants from infectious

diseases

• The composition changes over a single feeding, over a day, based on age of the infant, presence of infection in the breast, with menses, & maternal nutrition status

Colostrum

• The first milk secreted during the first few days postpartum

• Very high in proteins such as secretory IgA & lactoferrin

Water and Energy in Human Milk

• Water– Major component in human milk– Isotonic with maternal plasma

• Energy– ~0.65 kcal/mL– Calories may vary with fat, protein and

carbohydrate composition– Lower in calories than human milk substitute

(HMS)

Lipids in Human Milk

• Lipids—provide ½ the calories in human milk

• Effect of maternal diet on fat composition– Fatty acid profile reflects dietary intake of

mother– Very fat diet with adequate CHO & protein,

milk is in medium-chain fatty acids

DHA, Trans Fatty Acids, and Cholesterol in Human Milk

• DHA (docosahexaenoic acid)– Essential for retinal development– Associated with higher IQ scores

• Trans fatty acids– Present in human milk from maternal diet

• Cholesterol– Higher in human milk than HMS– Early consumption of cholesterol through breast

milk appears to be related to lower blood cholesterol levels later in life

Proteins in Human Milk

• Total proteins– Lower than in whole cow’s milk (0.32 vs. 0.96

g/fl oz)– Have antiviral & antimicrobial effects

• Casein– Main protein in mature human milk– Facilitates calcium absorption

Proteins in Human Milk

• Whey– A soluble protein that precipitates by acid or

enzyme– Some minerals, hormones & vitamin binding

proteins are part of whey– Includes lactoferrin, an iron carrier

• Non-protein nitrogen– ~20-25% nitrogen in human milk– Used to make non-essential amino acids

Milk Carbohydrates

• Lactose– Dominant CHO– Enhances calcium absorption

• Oligosaccharides– A medium-length CHO – Prevent binding of pathogenic

microorganisms to gut, which prevents infection & diarrhea

Fat-Soluble Vitaminsin Human Milk

• Vitamin A– Content in colostrum is ~double that of mature

milk– Yellow color from beta-carotene

• Vitamin D– Most as 25-OH2 vitamin D and D3

– Content reflective of mother’s exposure to sun

Fat-Soluble Vitamins

• Vitamin E– Level linked to milk’s fat content– Level not adequate to meet needs of preterm

infants

• Vitamin K– ~5% of breastfed infants at risk for K

deficiency based on clotting factors– Infants who did not receive K injection at birth

may be deficient

Water-Soluble Vitaminsin Human Milk

• Water soluble in general– Content reflective of mother’s diet or supplements– Vitamin most likely to be deficient is B6

• Vitamin B12 and folate– Bound to whey proteins– Low B12 seen in women who:

• Have hypothyroidism or latent pernicious anemia • Are vegans or malnourished• Have had gastric bypass

Minerals in Human Milk

• Minerals contribute to osmolality– Content related to growth of infant– Concentration decreases over first 4 months,

except for magnesium

• Bioavailability– Most have high bioavailability– Exclusively breastfed infants have very low

risk of anemia despite low iron content of human milk

Minerals in Human Milk

• Zinc– Bound to protein & highly available– Rare defect in mammary gland uptake of zinc

may cause zinc deficiency that appears as diaper rash

• Trace minerals– Copper, selenium, chromium, manganese,

molybdenum, nickel, fluoride– In general, trace minerals are not altered by

mother’s diet, except fluoride

Taste of Human Milk

• Flavor of foods in mother’s diet influences taste of breast milk– Infants seem more interested in mother’s milk

if flavor is new

• Exposure to a variety of flavors may contribute to infant’s interest & acceptance of new flavors in solid foods

Benefits of Breastfeedingfor Women

• Hormonal benefits– Increased oxytocin stimulates uterus to return

to prepregnancy status

• Physical benefits– Delay in monthly ovulation resulting in longer

intervals between pregnancies

• Psychological benefits– Increased self-confidence & bonding with

infant

Benefits of Breastfeedingfor Infants

• Nutritional benefits– Widely recognized– HMS (Human Milk Subs) use human milk as a

standard– Nutrients are balanced– Human milk is isosmotic– Meets infants’ protein needs without overloading the

kidneys– Contains soft, easily digestible curd– Provides generous amounts of the right lipids– Minerals more bioavailable

Benefits of Breastfeedingfor Infants

• Immunological benefits– Lower infant mortality in developing countries– Fewer acute illnesses

• Reductions in chronic illnesses– Reduce risk of celiac disease, IBS, leukemia– Reduce risk of allergies and asthmatic disease

• Breastfeeding & childhood overweight– Typically breastfed infants are leaner at 1 year of age

Benefits of Breastfeedingfor Infants

• Cognitive benefits– Studies show an increase in cognitive ability

even after adjusting for family environment

• Analgesic effects– Reduction of infant pain

• Socioeconomic benefits– Decreased need for medical care

Breast Milk Supply and Demand

• Can women make enough milk?– Milk synthesis is related to:

• How vigorously an infant nurses• How much time the infant is at the breast• How many times per day infant nurses

• The size of the breast does NOT limit a woman’s ability to nurse

• Is feeding frequency related to the amount of milk a woman makes?– Rate of milk synthesis is variable between

breasts & between feedings

Breast Milk Supply and Demand

• Pumping or expressing milk– Several different methods are available

• Manually• Hand pumps• Commercial electric pumps• Hospital grade electric pumps

– To stimulate adequate milk may require 8-12 expressions per day

Breast Milk Supply and Demand

• Can women breastfeed after breast reduction/augmentation?– The type of surgery determines the ability to

breastfeed

• Does silicone from breast implants leach into the milk?– There is no evidence of direct toxicity to the

infant

Positions for Breastfeeding

Attachment

The Breastfeeding Infant

• Reflexes– Gag reflex—prevents infant from taking food and

fluids into lungs

– Oral search reflex—infant opens mouth wide when close to breast & thrusting tongue forward

– Rooting reflex—infant turns to side when stimulated on that side

• Also requires appropriate positioning , adequate letdown and milk production

The Breastfeeding Infant

• Identifying hunger and satiety– Hunger is signaled by infant bringing hands to mouth,

sucking on them, & moving head from side to side– Crying is late sign of hunger– Allow infant to nurse on one breast as long as they

want to ensure they get hindmilk with its high fat content that provides satiety

• Note: High lactose content of foremilk may cause diarrhea

The Breastfeeding Infant

• Feeding frequency– 10-12 feedings/day are normal for newborns– Stomach emptying occurs in ~1½ hours

Identifying Breastfeeding Malnutrition

• Normal weight loss for newborns – ~7% of birthweight in 1st week– Weight loss of 10% needs evaluation by

lactation consultant

• Malnourished infants become sleepy, non-responsive, have a weak cry, & wet few diapers– By day 5 to 7, infants should have 6 wet

diapers & 3-4 soiled diapers

Tooth Decay

• Caries can occur in children who are breastfed

• Risk factor is frequent nursing at night after 1 year

• All children should be seen 6 months after 1st tooth erupts or at 1 year of age

Vitamin Supplements

• Vitamin supplements for breastfeeding infants– Vitamin K—all U.S. infants receive injections

at birth– Vitamin D—exclusively breastfed infants need

supplements at 2 months– No recommendations for fluoride or iron

Maternal Diet

• MyPlate Food Guide has been adapted for pregnant and breastfeeding women– Dietary Guidelines

• Moderate weight reduction can be achieved without compromising the weight gain of the infant

– Diets formed around a MyPlate food plan for pregnant and breastfeeding women provide

• Healthy assortment of nutrients at specified calorie levels for each stage of breastfeeding

Energy and Nutrient Needs for Lactation

• Energy needs vary by activity level

• DRI is 500 kcal/day for the 1st 6 months & 400 kcal/day afterward

• A single recommendation for energy needs could never address all of the individual variation in energy needs

Maternal Energy Balance and Milk Composition

• Protein-calorie malnutrition – Results in reduction in milk volume but not

quality

• Weight loss during breastfeeding– the caloric DRI assume a loss of 0.8 kg/month– Most women do not reach prepregnancy

weight by 1 year after birth– Modest or short-term energy reductions do

not decrease milk production

Exercising and Breastfeeding

• Modest energy restriction combined with increased activity may help women lose weight & body fat

• Exercise does not inhibit milk production or infant growth

Other Factors of Maternal Diet

• Vitamin and mineral supplements– Not needed in well-nourished women

• Functional foods– No adverse effects based on studies to date

Other Factors of Maternal Diet

• Fluids– Women should drink to thirst

• Alternative diets– Type of diet determines supplement that may

be needed

Other Factors of Maternal Diet

• Infant Colic– Defined as crying for more than 3 hours a day

– no medical cause– Components of maternal diet may be related

to infant colic– More likely with

• Cow’s milk, onions, cabbage, broccoli, & chocolate

Factors Influencing Breastfeeding Initiation and Duration

• Optimal duration of breastfeeding– AAP and Academy of Nutrition and Dietetics 1 year or

longer– U.S. Surgeon General exclusively for 6 months & best to

breastfeed for 12 months

• Obesity and breastfeeding– Overweight & obesity prior to pregnancy & excess

prenatal weight gain breastfeed for shorter duration

• Socioeconomic– Both low-income & more affluent mothers need

breastfeeding support

Barriers to Breastfeeding Initiation

• Embarrassment

• Time & social constraints

• Lack of support from family & friends

• Lack of confidence

• Concerns about diet & health

• Fear of pain

Breastfeeding Goals for the United States

• Healthy People 2020 breastfeeding objectives:– Increase proportion of infants breastfed– Increase duration of breastfeeding– Increase worksite lactation programs– Reduce formula supplementation in first 2

days of life– Increase births in facilities providing

recommended care for breastfeeding mothers

Breastfeeding Promotion, Facilitation, and Support

• Role of healthcare system in supporting breastfeeding– Health care system plays an influential role– AAP/MCHB Breastfeeding Promotion in Physicians

Office Practices

• Prenatal breastfeeding education and support– The Best Start Approach (see Table 6.7)– Prenatal education is effective in increasing number

who chose to breastfeed

Breastfeeding Promotion, Facilitation, and Support

Breastfeeding Promotion, Facilitation, and Support

• Lactation support in hospitals and birthing centers– Hospital practices can influence breastfeeding– Distribution of free formula samples is

discouraged– Baby Friendly Hospital Initiative established in

1992– UNICEF and WHO – Global Strategy for

Infant and Young Child Feeding 2002

Lactation Support after Discharge

• Breastfeeding support is essential in the first few weeks after delivery, as lactation is being established

• A pediatrician, nurse or other knowledgeable health care practitioner should see all breastfed infants at 2-4 days of age

• Le Leche League– Founded in 1956– International organization that provides education,

information, support & encouragement to women who want to breastfeed

Breastfeeding Promotion, Facilitation, and Support

• The work place– Barriers exist such as lack of on-site day care– Insufficiently paid maternity leave– Rigid work schedules– Lack of understanding/knowledge by

employers– Legislation is in progress to support

breastfeeding or pumping in the workplace

Breastfeeding Promotion, Facilitation, and Support

• The community– Establish a multidisciplinary breastfeeding

task force with representatives from:• Physicians• Hospitals and birthing centers• Public health• Home visitors• La Leche League• Government, industry, & school boards• Journalists

Breastfeeding Promotion, Facilitation, and Support

• The community– Community attitudes and obstacles to

breastfeeding need to be assessed– Barriers to breastfeeding may include

• Lack of access to reliable & culturally appropriate sources of information and social support

• Cultural perceptions of bottle feeding as norm• Aggressive marketing by formula companies• Laws that prohibit breastfeeding in public

Landmark U.S. Breastfeeding Policy

Model Breastfeeding Promotion Programs

• WIC National Breastfeeding Promotion Project—Loving Support Makes Breastfeeding Work– Loving Support to Grow and Glow

• Office of Women’s Health - Business Case for Breastfeeding

• Wellstart International