What are FODMAPs?
FODMAP is an acronym for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are a group of short-chain carbohydrates and sugar alcohols (polyols) found in grains, vegetables, legumes, milk, fruit and sweetened products.
These carbohydrates resist digestion, inhibiting their breakdown into smaller compounds, causing them to be poorly absorbed within the small intestine. Due to the poor absorption of these carbohydrates, they pass into the colon where they undergo fermentation by bacteria – acting as a beneficial prebiotic. But, in some individuals, this fermentation process, alongside the tendency of these carbohydrates to draw water into the colon, may result in a number of gastrointestinal symptoms. These symptoms include:
- Altered bowel movements (diarrhoea or constipation)
- Abdominal pain
These undesirable symptoms experienced from the consumption of high FODMAP foods is heightened by individuals with underlying gastrointestinal disorders such as irritable bowel syndrome (IBS) or an imbalance of bacteria within the gut.
Eliminating foods high in these carbohydrates is known as phase one of a low–FODMAP diet. By removing the consumption of these foods, the fermentation and increased water drawn into the colon from the presence of these carbohydrates is significantly decreased, as are the associated symptoms.
Many patients are misled into thinking that eliminating these foods from their diet is an appropriate long-term solution to their gastrointestinal issues as they experience a reduction in their symptoms. However, elimination is only phase one of the four phases of a low-FODMAP diet and adherence to the following phases is essential for long-term health outcomes. High-FODMAP foods make up a substantial proportion of a normal healthy diet and therefore should not be eliminated from the diet for a period of time greater than six weeks.
The subsequent phases of a low-FODMAP diet include the reintroduction phase, the trial-diet phase and the maintenance phase. Consulting with your naturopath throughout the process of a low FODMAP diet is fundamental to ensuring this diet is correctly implemented with minimal adverse effects and positive long-term health outcomes.
Furthermore, following a low-FODMAP diet may assist in the symptomatic relief of gastrointestinal symptoms but does not address the underlying cause of gastrointestinal issues.
Why FODMAPs do not address the issue
If a patient has been suffering from small intestinal bacterial overgrowth (SIBO) associated symptoms, it is likely they have tried a low-FODMAP diet and noticed significant improvements in their symptoms. This is because diets low in FODMAPs do decrease IBS symptoms. However, they don’t address the cause, which is ultimately SIBO. A low-FODMAP (or low-carbohydrate) diet will keep symptoms under control because it decreases the availability of the sugars in FODMAP foods in the gut, which are poorly absorbed in SIBO patients due to inflammation of the small intestine. These sugars act as a food source for bacteria overgrown in SIBO. When these bacteria don’t have food to eat, they aren’t able to metabolise that food and produce gas. This gas is what causes the common symptoms of SIBO—bloating, abdominal pain, diarrhea (in the case of hydrogen gas), and constipation (in the case of methane gas). For further information on SIBO and the symptoms associated with this condition, check out our SIBO blog post here.
Starving the bacteria over the short term may decrease symptoms but it does not eradicate the bacteria, it just leads to the bacteria lying dormant until food becomes available again. Furthermore, FODMAPs are actually fermentable carbohydrates that help feed the beneficial bacteria in the large intestine which is vital to our health. This is why long-term FODMAP restriction is not desirable. Rather, it is important to address the underlying bacterial overgrowth. Studies that examine the effects of FODMAP restriction show exactly what we imagine would happen when restricting these beneficial substrates. The overall amount of good probiotic bacteria (i.e. lactobacillus and bifidobacterium) in the large intestine is decreased. Moreover, long-term FODMAP diets are extremely restrictive. This can lead to feelings of stress and isolation which is also not healthy. A low-FODMAP diet has its place as part of reducing symptoms in SIBO patients, however it should never be long term.
Ultimately, it is not necessary to fully remove all FODMAP foods. We don’t want to try solving one problem, only to end up creating another. In saying that, foods which cause symptoms in a patient should be removed. These foods can be detected using a food diary. After successful treatment of the underlying drivers of SIBO, a patient may be able to tolerate and reintroduce FODMAP foods which previously caused a reaction in them, or at least add these foods in small doses, although there may be some foods they are never able to tolerate again.
Why FODMAP foods are essential to a healthy diet
High-FODMAP foods are high in fibre and are highly fermentable. Removing these foods from your diet completely means you’re also depriving yourself of the benefits these foods provide to the health of your gut and your overall health. Diets high in fibre and highly fermentable carbohydrates are positively associated with:
- Healthy and regular bowel movements
- Altering the pH level of the bowel and, in turn, inhibiting the growth of pathogenic bacteria and promoting growth of beneficial bacteria
- Decreased risk of colorectal cancer
- Reduced risk of cardiovascular disease and a number of contributing factors
- Reduced risk of type 2 diabetes
- Glycaemic control
- Prevention of weight gain and promotion of weight maintenance
- Satiation and satiety
- Improved gut barrier function and growth of colonic cells
- Enhanced mineral absorption
- Improved immune function
- Reduced inflammation and symptoms associated with inflammatory bowel disease.
With a better understanding of the beneficial roles these carbohydrates play in our health, it is easy to see why removing high FODMAP foods long term is not recommended.
Did you know Karly is writing a book on SIBO?
In collaboration with Melbourne-based naturopath, Alon Blumgart, Karly is writing an ebook on the subject of SIBO and which is designed specifically for use by practitioners. Both Karly and Alon are incredibly passionate about the condition and researching the best clinical treatments available for SIBO patients.
To book an appointment with our naturopath, Karly, click here.
Karly Fisher – Naturopath & Nutritionist
Alon Blumgart – Naturopath & Nutritionist