5.8 FODMAP Diet

We have reviewed the current evidence for a low starchy and refined carbohydrate diet with good quality fats in the form of different diets and nutrition plans including the Paleo diet and GI diet. There’s no doubt that health benefits can be ascribed to eating more vegetables on a daily basis and also for many people including daily low GI grains and legumes, such as rice and lentils, provides many important nutrients including complex carbohydrates, fibre, B vitamins and minerals.

However, an increasing number of people suffer from a rise in adverse food reactions (i.e. food intolerances and allergies) leading to Irritable Bowel Syndrome (IBS) including symptoms such as chronic gastrointestinal (GI) patterns of diarrhoea and/or constipation resulting in feelings of incomplete bowel evacuation, bloating, flatulence, abdominal pain and cramps, mucus in the stools, as well as anxiety, fatigue and loss of quality of life.

Diet is an obvious place to start to reduce reactive foods and improve the structure, integrity and digestive function of the bowel. This is where more directional individualised diets and nutrition plans can make difference to symptoms presentation and improvements to health. Please read the following article, which makes up part of the module content:

• Understanding Irritable Bowel Syndrome (IBS) can lead to solutions

IBS does not usually resolve without intervention and the gut is likely to remain predisposed to lifelong sensitivities once an initial IBS flare up occurs. In fact some of the contributory factors, such as intestinal permeability (colloquially called Leaky Gut Syndrome) and dysbiosis, may increase the risk of developing more complicated, deep-seated Inflammatory Bowel Diseases like Ulcerative Colitis and Crohn’s Disease. Other studies have drawn links between IBS, intestinal permeability and dysbiosis as risk factors for developing atopic conditions in the lung and skin, like asthma and eczema, psoriasis, as well as autoimmune disorders of the thyroid (e.g. hypothyroidism) and joints (e.g. arthritis).

If you’re interested in this area then please read the following three references:

• Porter, C. et al (2012) Risk of inflammatory bowel disease following a diagnosis of irritable bowel syndrome. BMC Gastroenterology 2012, 12:55 Full paper
• Turne, J. (2009) Intestinal mucosal barrier function in health and disease. Nat Rev Immunol 9:799-809 Full paper
• Tobin, et al (2008) Atopic irritable bowel syndrome: a novel subgroup of IBS with allergic manifestations. Ann Allergy Asthma & Immunol 100:49–53 Full paper

There is increasing acceptance that several contributory factors cause IBS symptoms including:

• Gut bacteria imbalances (dysbiosis)
• Gut barrier disruption (intestinal permeability or Leaky Gut Syndrome)
• Inflammation
• Gut immune system imbalances
• Poor digestion (malabsorption and nutrient deficiencies)
• Gut-brain axis disruption (e.g. stress)

Infection by parasites and yeasts like Candida may also be a contributory factor to IBS.

We have discussed imbalances in digestive and nervous system function in Part 1 of the Advanced course. In this section we are going to explore foods and diets to specifically support digestive function and integrity.

With so many different contributory causes and potential starting points for an IBS functional nutrition programme, a systematic approach is required.

The 5Rs Approach to Gut Healing

A proven superior and easy to follow functional nutrition paradigm for IBS management is based around the 5Rs:

1. REMOVE offending food or gastrointestinal infections/ bacteria imbalances.
2. REPLACE necessary digestive support.
3. REPOPULATE levels of beneficial gut bacteria.
4. REPAIR the gut barrier.
5. REBALANCE by addressing lifestyle, psychological issues and stress.

By carefully considering the case history and presenting IBS symptoms, the 5R programme implements food, nutritional supplements and lifestyle management as therapeutic tools to address the underlying causes and contributory factors providing a holistic and comprehensive approach to IBS management. The 5R programme also encourages the development of fundamental lifestyle changes to manage this condition and prevent the potential onset of other conditions.

There is plenty of evidence to suggest that various dietary constituents exacerbate IBS symptoms and may even contribute to the pathogenesis of IBS. This means the diet is one of the main therapeutic interventions that can be successfully manipulated to provide great relief and support for IBS symptoms. A myriad different IBS dietary approaches have gained popularity in recent years. However, IBS symptoms and causes vary from person to person so there can be no single magic IBS diet or “one size fits all” approach. The functional nutrition approach to IBS diet aims to support beneficial gut bacteria species and levels, balancing immune system activity and repair of the gut mucosal barrier.

If you’re interested in this area then please read the following references:

• Eswaran, S. et al (2011) Food: the forgotten factor in the irritable bowel syndrome. Gastroenterol Clin North Am. 40:141-162 Full paper
• Gibson, P. (2013) Functional bowel symptoms and diet. Intern Med J 43(10):1067-74 Full paper

Diet, Food Allergies & Intolerances in IBS

Many people with IBS find they experience adverse reactions to a range of different foods. Research shows that for some people food allergies and intolerances are implicated in IBS, especially the diarrhoea predominant type. Please read the following article, which makes up part of the course content:

• IBS and food – Is there a link?

One study identified raised levels of IgG antibodies to common foods such as wheat, indicating a delayed hypersensitivity reaction (the response frequently seen in food intolerances) in the blood of people with IBS. IgE antibodies were also detected in some IBS sufferers indicating an immediate immune system reaction, the same response found in allergic reactions. However, some reviews suggested there is no consistent evidence linking antibody-mediated food allergies and intolerances to all cases of IBS. These studies further underline the multifactorial nature to this condition and that for some people gut barrier repair and toxic load may be a greater factor in their IBS symptoms.

As not all cases of IBS have a measurable antibody-mediated immune reaction to certain food proteins, relying on food allergy testing may not be the most useful route to manage IBS. Food allergy tests are also limited in what foods they assess and the accuracy. For example, a person may receive a negative gluten blood test but in real life they still experience GI symptoms when eating gluten. This is often due to the sensitivity of the test, which may be limited to measuring just a couple of types of gluten. This means someone may react to a gluten fraction that is not included in the test panel hence the negative test result! Also, if someone takes a food intolerance/allergy test and has not eaten a particular food for a while then the body may not be producing sufficient detectable antibodies. Other tests use raw food test substrates and the person may only react to food that has been cooked – raw egg is not a staple in the UK diet! We will discuss functional tests further in Module 8.

Gluten & IBS

Growing evidence suggests that gluten; a collection of proteins found in grains like wheat, rye and barley, can damage the delicate gut lining.[9] These specific protein fractions, including different types of gliadin, are found in high levels in wheat products like bread. The body does not naturally produce a digestive enzyme to break down gluten resulting in levels that can damage the gut lining and tight junctions and trigger antibody-mediated responses. This means gluten can contribute to many digestive problems like IBS, as well as other inflammatory conditions including autoimmune and inflammatory diseases like arthritis and cardiovascular disease.

Gluten proteins have been shown to trigger a breakdown of the internal support scaffold of the gut epithelial cells leading to a change in cell structure. Once the actin filaments in the intestinal epithelial cell cytoskeleton are damaged by gluten, the tight junctions between the intestinal cells are disrupted increasing intestinal permeability. The direct impact of different gluten proteins on the tight junction zonulin proteins allows the contents of the gastrointestinal tract to directly leak into the blood stream (i.e. intestinal permeability or Leaky Gut Syndrome). Gluten fractions can also directly stimulate the gut immune system causing increased inflammation, damage to the gut lining and increased levels of reactive antibodies.

There is a spectrum of gluten sensitivity within the population. Some people can tolerate a little dietary gluten, but should assess their diets to achieve a better balance by replacing gluten products like bread and pasta with naturally gluten free low GI grains, such as brown rice, quinoa and gluten free oats. However, people with IBS should REMOVE gluten-containing foods from the initial dietary programme due to the damage and inflammation that can be caused within the intestinal tract, contributing to symptoms such as IBS pain and bloating.

Plant based digestive enzyme supplements containing gluten digesting enzymes are a useful addition to an IBS programme to tackle any residual forms of dietary gluten (see REPLACE stage of 5R programme). For some people, a small amount of gluten may be gradually reintroduced back into the diet after a few months to alleviate dietary restrictions – see FODMAP Diet Guidelines for how to reintroduce foods. However, gluten sensitivities are rife in the population (often grouped as non-coeliac gluten sensitivity) contributing to long-term immune system issues, gut barrier sensitivities and other chronic conditions long after IBS symptoms may have subsided. For these reasons it is generally considered best by many functional practitioners to continue with a gluten free diet for long-term bowel and immune health.

Dairy & IBS

Processed dairy products, like cheese and pasteurised milk, form a large part of many Western diets. Like gluten, adults do not have a digestive enzyme in the gut to breakdown the constituents of milk including the milk sugar lactose and milk protein casein. Many people are lactose intolerant or may have an immune mediated reaction to casein contributing to gut barrier damage, dysbiosis and IBS symptoms.

The gut, like other epithelial surfaces within the body including the lung and nasal linings, requires a protective layer of mucus, secreted as mucin by goblet cells. The mucin layer protects the gut cells and also provides a platform for the beneficial gut bacteria to grow, which in turn regulates goblet cell mucus secretion. Some practitioners suggest that dairy products can increase mucus production in the gut (and other epithelial surfaces) potentially disrupting GI barrier function and contributing to dysbiosis, as well as immune system dysfunction. Therefore it’s highly recommended to REMOVE dairy from an IBS management programme. Reintroduction of some dairy products such as butter or live yoghurt during later stages of the 5R programme can be achieved along the same lines as gluten, if applicable.

Fibre & IBS

As we have previously discussed, fibre is essential for a healthy gut and gut microbiota, as well as regulating blood sugar, fat and cholesterol levels to support cardiovascular health. However, the fermentation gases produced when eating certain types fibre (e.g. high FODMAP foods) can contribute to and worsen IBS symptoms. Certain insoluble fibres like wheat bran can also have an abrasive action, causing further GI damage and inflammation in people with IBS. So how should fibre be managed in an IBS programme?

Restricting FODMAPs, and other high fibre foods like beans and pulses, for a few weeks has been shown to improve stool consistency for patients with both diarrhoea and constipation predominant IBS. The mechanism by which constipation improves on the low FODMAP diet may be related to reduced methane production. The improvement of symptoms by removing high fibre foods alongside following the other elements of the 5R programme to support gut repair and improve digestive function allows for phased reintroduction of higher fibre foods as the programme progresses.

Psyllium is a type of fibre that has several benefits in IBS. Traditionally, a small amount of psyllium fibre can be used to bulk the stools and ease constipation – a feature for some people with IBS. New research has shed light on the several active components, including natural sterols, mucilage, arabinoxylans and fatty acids, which in combination have specific anti-spasmodic activity helping to relieve diarrhoea. This makes psyllium husk a unique type of fibre for regulating gut function in both constipation and diarrhoea predominant IBS. Psyllium fibre has also been shown to act as a prebiotic, increasing the number of beneficial bifidobacteria in the colon.

FODMAP Diet & IBS

There are other food sensitivities that can contribute to IBS symptoms without triggering an immune mediated response, as seen with gluten or dairy. Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols (FODMAPs: Figure 5.9; Table 5.3) are a family of poorly absorbed short chain carbohydrates (also considered a type of fibre), which are highly fermentable in the presence of gut bacteria.

In a healthy colon, fermentation of different types of soluble fibres, including from FODMAP sources, produce short chain fatty acids (SCFAs), as well as gases (methane, hydrogen and carbon dioxide). SCFAs are absorbed into the blood stream and used for energy, as well as nourishing the cells of the colon and acting as a prebiotic source promoting healthy gut bacteria growth and balance. As such, FODMAPs are important to bowel health.

However, in IBS where dysbiosis throughout the small (SIBO) and large intestines is prevalent, FODMAPs can lead to greatly increased fermentation. Intestinal permeability can also mean that FODMAPs are absorbed through the gut wall creating an osmotic effects resulting in increased delivery of water through the bowel. All these effects cause excess gas production and increased fluid load that expands the small bowel wall leading to increased GI muscle contractions resulting in diarrhoea, bloating and cramping. However, for some people with IBS the excess gas may slow movement of the bowel contributing to constipation.

FODMAP Diet Framework

Studies have shown that restricting dietary FODMAPs can offer up to 86% relief of overall gastrointestinal IBS symptoms, specifically bloating, excess flatulence, abdominal pain and altered bowel habits. It’s also a dietary approach that 76% people on one study were able to adhere to and 72% were satisfied with reduction of their symptoms.

The FODMAP diet REMOVES high FODMAP food for six to eight weeks, alongside implementing other relevant stages of the 5R programme, and monitoring IBS symptoms. After six to eight weeks, FODMAP foods can be gradually reintroduced based on symptom response, relieving the dietary restriction though often long-term restriction of processed gluten and dairy foods is still advised.

Table 5.3 High and Low FODMAP Foods

 Table 5.4 Example of FODMAP diet meals

Reintroduction of FODMAP foods

1. Test 1 FODMAP group at a time.
2. Work out an appropriate portion size, as too much or too little may affect how the results.
3. Continue to restrict all other FODMAPs until tolerance or intolerance is confirmed.
4. Don’t make other dietary changes.
5. Challenge with one FODMAP group per week and monitor symptoms:

• First FODMAP group to test is polyols – try eating ½ avocado or 2 fresh apricots.
  • Increase to foods containing mannitol including ½ cup cauliflower and ½ cup mushrooms.
  • If all is going well try introducing lactose or fructose (e.g. ½ mango, 4tbsp live yoghurt or 1tsp honey).
  • Final group is galacto oligosaccharides such as ½ cup lentils, kidney beans or chickpeas.

6. Eat the challenge food at least twice during the test week unless you get a reaction in first attempt, in which case stop.
7. If you don’t get symptoms then increase range of FODMAP foods.
8. If you do get symptoms either reduce the amount of test, try another FODMAP food group or continue to restrict FODMAPs and progress with the 5R IBS programme for continued gut healing and bacteria support.

Example reintroduction programme is outlined in Table 5.5:

Table 5.5 The reintroduction phase of the low FODMAP diet

For full information about the 5R programme please read the nutrihub education article on Irritable Bowel Syndrome

 FODMAP diet summary

• Low FODMAP diet forms part of the 5R programme to support gut health and manage IBS.
• This is a short-term diet to repair the integrity of the digestive tract, improve digestion and address dysbiosis.
• Excluding high FODMAP excludes a number of important nutrient food groups so adherence to this diet is for six to eight weeks only before phased reintroduction of different FODMAP groups.

Please make sure you’ve read the articles, which contribute to the content of this section:

• Understanding Irritable Bowel Syndrome (IBS) can lead to solutions
• IBS and food – Is there a link?

If you are interested in any of the 5R areas and the research behind supporting these areas then please refer to the nutrihub education article for full reference listing:

• nutrihub education article on Irritable Bowel Syndrome

References

• Porter, C. et al (2012) Risk of inflammatory bowel disease following a diagnosis of irritable bowel syndrome. BMC Gastroenterology 2012, 12:55 Full paper
• Turne, J. (2009) Intestinal mucosal barrier function in health and disease. Nat Rev Immunol 9:799-809 Full paper
• Tobin, et al (2008) Atopic irritable bowel syndrome: a novel subgroup of IBS with allergic manifestations. Ann Allergy Asthma & Immunol 100:49–53 Full paper
• Eswaran, S. et al (2011) Food: the forgotten factor in the irritable bowel syndrome. Gastroenterol Clin North Am. 40:141-162 Full paper
• Gibson, P. (2013) Functional bowel symptoms and diet. Intern Med J 43(10):1067-74 Full paper