How the Low FODMAPs Diet Reduces IBS Symptoms€¦ · Web viewAdditionally, GI symptoms of IBS...

How the Low FODMAPs Diet Reduces IBS Symptoms

Lisa L. Schmitt11-8-2019


Introduction

Irritable Bowel Syndrome (IBS) is a gastrointestinal (GI) disorder for which most

prescribed therapies do not work effectively to relieve symptoms (Mahan, Escott-Stump &

Raymond, 2012). However, a diet therapy that limits the intake of FODMAPs has been shown to

be effective in the reduction and management of GI symptoms, such as abdominal pain, bloating,

gas, diarrhea and or constipation in IBS patients ("FODMAPs", 2019). The Low FODMAP Diet

(LFD) was created by Monash University researchers as a dietary treatment to alleviate the

symptoms of IBS ("FODMAPs", 2019). The mechanism behind the principle of LFD is to reduce

the intake of FODMAPs to a level where IBS symptoms are well-controlled. FODMAPs are

short chain carbohydrates that are not easily digested and absorbed in people who have IBS. The

LFD is currently thought to be the most effective treatment for IBS patients.

About IBS

IBS is a very common chronic GI disorder. The pathophysiology of IBS appears to be

multifaceted. Altered GI function, disordered brain-gut signaling, and psychosocial factors are

thought to have roles in the onset of symptoms (Staudacher & Whelan, 2017). Additionally, GI

symptoms of IBS often cause other side-effects, such as “anxiety and depression, decreased work

productivity and activity impairment, and decreased quality of sleep and increased fatigue”

(Eswaran, Chey, Jackson, Pillai, Chey & Han-Markey, 2017). Generally, many IBS sufferers

experience an overall decreased quality of life (Scarlata, 2018). IBS also contributes

considerably to healthcare costs, with 30% of primary care visits and up to 60% of

gastroenterology referrals related to IBS, accounting for up to $1.66 billion in the United States

(Staudacher & Whelan, 2017).

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The diagnosis of IBS is based on an assessment of symptoms and the Rome III criteria, as

can be seen in Figure 1 below. (Figure 1, Kortlever, Hebblethwaite, Leeper, O'Brien, Mulder, &

Gearry, R. B, 2016).

IBS is further classified into three subtypes: IBS-D for diarrhea prevalent, IBS-C for constipation

prevalent, and IBS-M for mixed stool consistencies (Mahan, et al., 2012).

FODMAPs – What are They?

FODMAPs is the acronym for fermentable oligosaccharides,

disaccharides, monosaccharides, and polyols. Oligosaccharides are fructans

and galacto-oligosaccharides (GOS) from wheat, rye, onions, garlic, and

legumes. Disaccharides are lactose found in milk and milk products.

Monosaccharides are fructose in excess of glucose found in fruit, vegetables,

and honey. Polyols are sorbitol and mannitol, sugar alcohols found in some

fruits and vegetables and used as artificial sweeteners ("FODMAPs", 2019).

Figure 2 provides a visual description of FODMAPs (FODMAPs image, 2019).

Mono- and disaccharides are digested and absorbed in the small intestine.

Fructans, GOS and polyols pass through the small intestine unabsorbed to be

fermented in the colon.

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Figure 1. Rome III Criteria for Diagnosing Irritable Bowel Syndrome


Mechanisms of Action of FODMAPs

When FODMAPs are ingested, bloating may be caused due to the osmotic effect of

excess unabsorbed sugars in the small intestine (Hill, Muir & Gibson, 2017). Additionally, the

release of gases from bacterial fermentation increases the volume of the gut and creates

distention (Hill, et al., 2017). Bloating and distention in the gut sends signals to the brain that

cause pain (Hill, et al., 2017). Water accumulation in the small intestine has been confirmed in

imaging studies following ingestion of FODMAPs (Kortlever, et al., 2016). A randomized,

single-blinded, cross-over study of twelve subjects with ileostomies observed a 20% increase in

“effluent weight, dry weight, and volume” following consumption of a high FODMAPs diet

(Kortlever, et al., 2016). Moreover, an MRI study found “small bowel water content (SBWC)”

increased after a large intake of fructose (Kortlever, et al., 2016). When fructose was taken

together with glucose, SBWC was reduced (Kortlever, et al., 2016). Fructose is absorbed via a

specific transporter called GLUT5 (Gropper & Smith, 2013). Under typical dietary intake

conditions, GLUT5 can effectively facilitate the absorption of fructose (Gropper & Smith, 2013).

However, fructose intake in excess of 50g has shown to cause malabsorption which has the

potential to trigger GI symptoms (Gropper & Smith, 2013).

Fermentation occurs when the FODMAP compounds; fructans, GOS, and polyols, pass

through the small intestine unabsorbed to the colon where bacteria ingest them for nutrients

("FODMAPs", 2019). The fermentation process creates excess gases such as carbon dioxide,

hydrogen, and methane (Staudacher & Whelan, 2017). Breath hydrogen tests are used to measure

fermentation of gut bacteria. A study by Ong et al, found that both IBS patients and healthy

subjects produced more breath hydrogen after ingesting a high FODMAP diet as compared to an

LFD (Kortlever, et al., 2016). Increased fermentation in the colon leads to increased levels of

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gases, as evidenced by hydrogen breath test results, thereby leading to onset of bloating and pain

symptoms for IBS sufferers. Figure 3 illustrates the effect of FODMAPs in both the small

intestine and large intestine. It is thought that the distension experienced by increase water

content in the small intestine and excess gases in large intestine send signals to the brain from the

gut that trigger abdominal pain (Staudacher & Whelan, 2017). Moreover, increased water in the

small intestine has been thought to lead to diarrhea.

Determining High and Low FODMAP Composition of Foods

Monash University has been working for over 10 years testing for FODMAPs content in

a wide variety of foods. This research is used to develop an extensive database of FODMAP

contents as well as cutoff values to distinguish between high and low FODMAP foods (Varney,

Barrett, Scarlata, Catsos, Gibson & Muir, 2017). While the current library is quite extensive,

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Figure 3: Mechanisms of the effects of FODMAPS on the small and large intestine.


interest in the LFD for the treatment of IBS has grown; therefore, the need to include more

FODMAP foods with cutoff values has grown with it (Varney, et al., 2017).

The technique for measuring FODMAP levels is different for each category of food. For

example, when testing fruits and vegetables, 500-gram samples are collected from five different

grocery stores and five different produce markets (Varney, et al., 2017). When testing grains and

cereal products, three samples; a name brand, a generic brand and one other; are collected. 100-

gram samples of each food are prepared, frozen, freeze-dried, then one gram of each sample is

extracted in 80ºC water. Samples are tested using high-performance liquid chromatography to

separate, identify, and measure individual components such as lactose, GOS, fructose in excess

of glucose, and polyols (Varney, et al., 2017). Fructan and fructose content is measured using

another test, the Megazyme Fructan HK Assay kit. Enzymes are added to samples to eliminate

sucrose and short chain maltosaccharides to isolate fructans, and then fructans are hydrolyzed

into fructose (Varney, et al., 2017).

With the results of these tests, FODMAP contents are established, and cutoff levels are

assigned to classify the food as either high or low FODMAP (Varney, et al., 2017). The cutoffs

include each FODMAP sugar in a food, including oligosaccharides, polyols, excess fructose and

fructose in excess of glucose, and lactose (Varney, et al., 2017). Cutoff values for each of the

FODMAPs categories is shown in Table 1 (Varney, et al., 2017).

The reliability of Monash University’s cutoff values has been rigorously tested (Varney,

et al., 2017). In a 2014 randomized controlled trial, the Monash cutoff values were used to design

diets low and high in FODMAPS (Varney, et al., 2017). In this study, when FODMAPs were

limited to no more than 0.5g per meal or snack, the LFD “led to statistically significant

improvements in IBS symptoms” (73.1 CI = 54.0-92.1, p<.001) as compared to the high

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FODMAPS diet (Halmos, Power, Shepherd, Gibson, & Muir, 2014). It can be concluded from

these results that the methods used to determine Monash University’s cutoff values are reliable,

therefore these guidelines may be used to design LFD for IBS patients.

Implementation of the Low FODMAP Diet

Before beginning the LFD, it is very important for the patient to be assessed and receive a

diagnosis of IBS by a physician using the Rome III criteria. IBS symptoms are like symptoms of

other possible diseases, such as celiac disease, endometriosis or colon cancer. Only patients with

IBS should follow this diet (“FODMAPs”, 2019). The LFD works best when it is delivered to

patients one-on-one by a Registered Dietitian Nutritionist (RDN) or other health professional

who has been trained (Hill, et al., 2017). RDNs can provide the most current and updated

information on FODMAP contents in food and ensure nutritional adequacy while providing a

varied diet (Wolfram, 2016). Additionally, an RDN will be able to direct the patient to sources of

information that are credible and accurate, as well as assist in the personalization of the diet to

the patient’s FODMAPs tolerance levels (Wolfram, 2016). In this way, compliance with the diet

will be increased thereby reducing symptoms of IBS.

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Table 1: Monash Cutoff values for each FODMAP (Varney, et al., 2017)


The LFD is a three-step diet. In the first step, which lasts for two-six weeks, the patient

swaps out high FODMAP foods for low FODMAP foods (“FODMAPs”, 2019). At about six

weeks, the patient can begin step two, the reintroduction of FODMAP foods. The patient begins

to add FODMAPs to their diet; one FODMAP at a time, one food at a time, and over a three-day

period (FODMAPs, 2019). The patient monitors their tolerance while increasing the serving size

each day (“FODMAPs”, 2019). The final step is the personalization of the FODMAP plan. By

this time, the patient should be able to identify foods that contain FODMAPS that either trigger

or control their IBS symptoms (“FODMAPs”, 2019). The goal is to find a long-term plan that

balances FODMAP foods while also ensuring the patient’s diet remains nutritionally adequate

(Kortlever, et al.,2016). The LFD minimizes the intake of food with a high content of

fermentable short chain carbohydrates, but it does not prohibit or eliminate them completely. The

goal is to reduce FODMAPs to a level where IBS symptoms are controlled.

To make it easier for IBS patients to adhere to the LFD, Monash University has created

an app to use on a smartphone. It includes a guide for cutoff values using red, yellow, and green

to symbolize high, moderate, and low FODMAPs for each food included, some recipes as well as

the complete FODMAP Diet Guide (Get the App, n.d.). Figure 3 illustrates some of the features

of the Monash University FODMAP Diet app.

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Figure 3. Monash University FODMAP Diet App (Get the App, n.d.).


Discussion

Evidence exists as to the effectiveness of LFDs diet in the treatment of IBS; however,

research has been limited to short-term studies. Many of these studies have been criticized as

being poor quality for several reason; i.e. too few subjects, lack of long-term follow-up, and not

utilizing a control group. However, the difficulty in designing and performing blinded studies

involving whole diet interventions is well-known (Kortlever, et al., 2016).

A 2014 randomized, controlled, single-blind, cross-over study with 38 subjects, 30

participants with IBS and 8 healthy participants, found a statistically significant reduction in

overall GI symptoms and individual symptoms of abdominal pain, bloating and dissatisfaction

with stool consistency on a LFD compared to a moderate FODMAP diet typical of the Australian

diet (Halmos, et al., 2014). While the number of participants in this interventional dietary study

was small, it was designed with strong controls; subjects were blinded to the diet, providing all

the food, and including a group of healthy control subjects. GI symptoms were scored on a scale

of 0 (no symptoms) to 100 (worst symptoms) and were recorded prior to each intervention and

during the last 14 days on the intervention diets. Mean overall baseline score of GI symptoms for

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IBS patients prior to LFD intervention was 36.0 (95% CI, 29.5-42.5) and after the intervention

mean score dropped to 22.8 (95% CI, 16.7-28.8) (Halmos, et al., 2014). The difference in the

mean score between the low-FODMAPs diet and the moderate FODMAP diet were statistically

significant (P < .001) for the IBS subjects. As you can see in Figure 4, GI symptoms decreased

within 7 days on the LFD and was maintained for the entire 21-day intervention, while GI

symptoms increased on the moderate FODMAP intervention.

It has been documented that many IBS patients experience decreased quality of life in

addition to debilitating GI symptoms. In a randomized controlled superiority trial, Eswaran et al.

(2017) concluded subjects on the LFD led to significant improvement in scores for “health-

related quality of life, anxiety, and activity impairment” as compared to subjects on the mNICE

diet, a diet therapy traditionally used as treatment for IBS-D patients (Eswaran, et al., 2017).

Eighty-four subjects with IBS-D completed the 4-week trial, and the participants on the LFD

reported a larger mean increase in IBS-QOL as measured by a questionnaire (15.9 vs. 5.0; 95%

CI, -17.4 to -4.3) (Eswaran, et al., 2017). Additionally, a higher number of patients in the LFD

group reported a “meaningful clinical response”, defined by the study as >14-point improvement

in score (52% vs. 21%; 95% CI, -0.52 to -0.08) (Eswaran, et al., 2017). Furthermore, anxiety

scores decreased in the LFD group compared to the mNICE group (1.63, 95%, CI 0.46-2.80)

(Eswaran, et al., 2017). Moreover, a significant reduction in activity impairment was reported in

the LFD group compared with mNICE (13.50, CI 2.72-24.20) (Eswaran, et al., 2017). This study

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Figure 4: Mean overall GI symptoms for the IBS cohort from baseline, low FODMAP and moderate FODMAP interventions. (Halmos, et al., 2014)


provides evidence that an LFD is an effective treatment option in order to improve quality of life

as well as GI symptoms for patients with IBS-D.

A 2017 meta-analysis of nine randomized controlled trials with a total of 596 subjects,

concluded there was a significant difference between the LFD diet and other diets when it comes

to controlling GI symptoms (SMD = -0.62; 95% CI = -0.9 to -0.31; p = 0.0001) ) (Schumann,

Klose, Lauche, Dobos, Langhorst & Cramer, 2017). Additionally, abdominal pain was reduced

(SMD = -0.50; CI = -0.77 to -0.22; p = 0.008), and health-related quality of life improved (SMD

= 0.36; CI = 0.10-0.62; p = 0.007) (Schumann, et al., 2017). Authors of this study concluded this

additional evidence points to the efficacy of the LFD in the short term, however

recommendations for long-term effectiveness requires further investigation (Schumann, et al.,

2017).

In a review of ten randomized controlled trials or randomized comparative trials,

Staudacher & Whelan (2017) noted one retrospective study that showed promising long-term

effects for 57%-75% of patients following a modified-FODMAP diet at 14-16 months

(Staudacher & Whelan, 2017). However, authors noted potential bias due to subject recall

(Staudacher & Whelan, 2017). Due to the chronic nature of IBS, further investigation to

determine the longevity of IBS symptom reduction, especially after reintroduction and

personalization, is warranted.

Given that some FODMAPs provide nutrients for the bacteria that reside in the gut, the

LFD might be likely to have a negative impact on the gut microbiome. These bacteria

demonstrate health-promoting characteristics such as boosting the immune system and

anticarcinogenic properties (Gropper & Smith, 2013). They also produce short-chain fatty acids

through fermentation, which increase the acidity of the gut, suppress pathogens, and maintain

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homeostasis (Staudacher & Whelan, 2017). Hill, et al. (2017) noted two studies that revealed a

reduction of Bifidobacteria in feces after subjects followed the LFD for 3-4 weeks (Hill, et al.,

2017). The negative effects of a reduction in gut bacteria have not been studied, nor has the

method of reestablishment of these bacteria after the reintroduction phase of the LFD been

considered (Kortlever, et al., 2016) It is indicated that due to the rapid reactions of gut

microbiota, a slow introduction of FODMAPs into the diet can return the gut microbiome to

normal (Staudacher & Whelan, 2017). In this way, IBS patients can maintain their symptom

control without unnecessary impairment to their gut microbiome. The concern over the effect of

low FODMAP on the gut microbiome merits further consideration.

Conclusion

The debilitating symptoms of pain, bloating, gas, constipation or diarrhea, as well as the

poor quality of life that IBS patients suffer from, have been attributed to the poor digestion and

absorption of FODMAPs. The evidence is strong that implementation of the LFD that restricts

intake of FODMAPs to 0.5g per meal or snack, is an effective treatment that can alleviate

symptoms within the elimination step of the diet (Halmos, et al., 2014). However, there is little

evidence that the LFD helps control IBS symptoms after implementation of reintroduction and

personalization steps of the diet; therefore, more research is needed in this area (Staudacher &

Whelan, 2017). Moreover, the LFD may have a harmful effect on the gut microbiome, therefore

additional research is necessary in this area to clarify the long-term consequences of the Low

FODMAP Diet (Kortlever, et al., 2016).

The LFD can be extremely difficult to adhere to and implementation of this nutrition

therapy should take place under the care of an RDN who is trained. The LFD is not meant to be a

lifelong dietary intervention, therefore careful reintroduction of FODMAPs to identify the

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patient’s trigger foods while maintaining the gut microbiota is crucial. Personalization of the

LFD will ensure nutritional adequacy and better compliance, and lead to improved GI symptoms

and overall quality of life for the many IBS sufferers around the world.

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References

Eswaran, S., Chey, W., Jackson, K., Pillai, S., Chey, S., & Han-Markey, T. (2017). A Diet Low

in Fermentable Oligo-, Di-, and Monosaccharides and Polyols Improves Quality of Life

and Reduces Activity Impairment in Patients with Irritable Bowel Syndrome and

Diarrhea. Clinical Gastroenterology and Hepatology, 15(12), 1890-1899.e3. doi:

10.1016/j.cgh.2017.06.044

FODMAPs and Irritable Bowel Syndrome. (2019). Retrieved from

https://www.monashfodmap.com/about-fodmap-and-ibs/

Fodmaps Image. (n.d.). Retrieved from

https://www.bbc.co.uk/food/articles/what_is_a_fodmap_diet

Get the App. (n.d.). Retrieved October 31, 2019, from https://www.monashfodmap.com/ibs-

central/i-have-ibs/get-the-app/

Gropper, S.S., Smith, J. L. (2013). Advanced Nutrition and Human Metabolism (6th ed.).

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FODMAPs Reduces Symptoms of Irritable Bowel Syndrome. Gastroenterology, 146(1),

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Kortlever, T., Hebblethwaite, C., Leeper, J., O'Brien, L., Mulder, C., & Gearry, R. B. (2016).

Low FODMAP diet efficacy in IBS patients-what is the evidence and what else do we

need to know? The New Zealand Medical Journal (Online), 129(1442), 75-83,5,

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https://www.nzma.org.nz/journal/read-the-journal/all-issues/2010-2019/2016/vol-129-no-

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Mahan, L. K., Escott-Stump, S., Raymond, J. L. (2012). Krause’s Food & The Nutrition Care

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Schumann, D., Klose, P., Lauche, R., Dobos, G., Langhorst, J., & Cramer, H. (2018). Low

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