FODMAP is not a single entity, but a group of an acronym that stands for fermented, oligo, di, monosaccharides and polyols. FODMAPs are found in a variety of fruits, vegetables, milk and wheat.
HOW FODMAP WORKS;
FODMAP may exacerbate IBS symptoms through a various mechanism such as ;
OSMOTIC OVERLOAD; Poor absorption of FODMAP causes osmotic overload and distention of small intestine and abdominal symptoms.
BACTERIAL FERMENTATION; FODMAPs are rapidly absorbed by colonic bacteria and produce colonic distention due to gas production associated with abdominal pain and bloating.
FODMAPs are not bad for everyone, in normal healthy individuals they have important physiological effects like; they increase stool bulk, enhance calcium absorption and modulate immune function. They selectively stimulate the growth of Bifidobacterium a species of good bacteria.
FODMAPs and the irritable bowel syndrome (IBS)
IBS is a chronic functional disorder of the intestine, the most common symptoms are abdominal pain, bloating and altered bowel movements.The global prevalence of IBS is around 12% and is more common in women.
Treatment of IBS consist of pharmacological and non pharmacological measures. Among the non pharmacological options; stress reduction, dietary modifications ( restriction of certain food (FODMAP) and cognitive behaviour therapy are the most important.
LOW FODMAP DIET
In recent years, there is a growing body of research which support low FODMAP diet for the management of IBS, studies have shown that it can help up to 70-85% of patients with IBS achieve relief of their symptoms. it is now included in NICE guidelines as a second line intervention for IBS.
Following a low fodmap diet may helpful in alleviating symptoms of IBS like
- Abdominal pain
- Altered bowel movement
There is no evidence that low FODMAP diet works for non digestive symptoms that are associated with IBS, such as headache and skin or joint problems.
Phases of low FODMAP diet
It is three phased elimination diet, first phase is the restriction phase in which high FODMAP food should be completely avoided. This phase lasts for 2-6 weeks. Second phase is reintroduction in which food with high FODMAP reintroduced but one at a time. This will enable you to identify which FODMAP you are sensitive too. This stage can take several months to complete and ideally should be completed under the guidance of a dietitian. Personalized stage the third phase is a combination of phase 1 and phase 2 and involves the long term, modified FODMAP diet. For more information regarding a high FODMAP food list https://www.monashfodmap.com/about-fodmap-and-ibs/high-and-low-fodmap-foods/
WHAT IS DOWNSIDES OF LOW FODMAP.
There is short term risk associated with insufficient protein, dietary fibre, B group vitamins and calcium intake.
Low levels of prebiotics;
Prebiotics are indigestible carbohydrates that are resistant to gastric acid and fermented by bacteria present in the large intestine. Prebiotics predominately found in food containing Fructans and Galacto-oligosaccharides.The low FODMAP diet restricts the intake of many high prebiotic (high FODMAP) foods and prolong restriction of high FODMAP can alter gut microbiome diversity. Studies have shown low levels of total bacterial abundance and reduced level of bifidobacterium following a low FODMAP diet. This is why re-introduction phase is very important as it allows you to have more variety in your diet but also maintain a healthy gut.
Calcium in low FODMAP diet;
The restriction of lactose containing dairy products may enhance the tendency to poor calcium availability since these items are primary source of calcium and promoting effect of lactose on calcium absorption is lost.
Lactose or dairy free calcium sources are; Kale, lactose free plant based milk fortified with calcium, hard cheese, firm tofu.
TAKE HOME MESSAGE
Low fodmap diet is considered as a second line treatment option for patients with IBS as recommended by NICE guidelines. This diet should not be used without specialized dietary advice from a registered professional. Vegan or vegetarian are at increased risk of protein deficiency due to limited plant protein sources however well constructed meal plans by registered dietitians may reduce possible nutritional deficiencies.