FODMAPs

FODMAPs is an acronym for Fermentable Oligo-saccharides, Di-saccharides, Mono-saccharides And Polyols.

FODMAPs are a group of sugars and short chain carbohydrates that are not absorbed in the small intestine (like dietary fibre and resistant starch). Bacteria in the large intestine (or even in the small intestine) ferment FODMAPs to produce large amounts of gas (hydrogen and methane), which can be very uncomfortable, particularly to those with irritable bowel syndrome. They can also act as a laxative by preventing excess water from being absorbed by the intestine

Irritable Bowel Syndrome is a common gastro-intestinal disorder characterized by abdominal bloating, excess gas, crampy pain and diarrhoea and/or constipation. Diagnosis is made on the basis of long-term symptoms and the exclusion of other causes such as inflammatory bowel disease (Crohn’s disease and Ulcerative colitis), Coeliac disease (caused by gluten in wheat and related grains) and other diseases. If you have Irritable Bowel Syndrome, a whole foods plant based diet will provide the high fibre diet that is recommended, but you may need to limit the quantities of some foods. As your gut health improves on a whole foods plant based diet you may find that you are better able to tolerate high FODMAP foods.

FODMAPs are comprised of several groups:

  1. Fructose
  2. Lactose
  3. Sugar polyols – sorbitol and mannitol
  4. Fructans and GOS (galacto-oligosaccharides).

Fructose and lactose are only a problem to individuals who lack the capacity to absorb them from the small intestine. Most non-European adults cannot absorb lactose but this is not an issue on a plant-based diet because lactose is only found in dairy products, not plants. There seems to be an epidemic of fructose intolerance. We suspect that this is related to the gut inflammation and gut bacteria imbalance that we discussed on the Gut Health page. Fructose absorption is assisted by glucose so it is really the excess fructose relative to glucose that causes problems. (Cane sugar is a di-saccharide of fructose and glucose so it’s not a FODMAP, just a concentrated carbohydrate devoid of any other nutrients). For more troublesome symptoms, you may consider taking a hydrogen breath test for fructose intolerance. Your doctor can request this test. The result may then guide you as to whether you may benefit by limiting high fructose foods, or conversely avoid unnecessary restriction of otherwise healthy fruits and vegetables.

The low FODMAP diet is not a total exclusion diet. It’s not like peanut allergy or gluten intolerance. Bacterial fermentation of undigested carbohydrate is part of the normal function of the human gut, and it only becomes a problem when there is too much gas produced too quickly, or that your gut is abnormally sensitive to distension. You can reduce the FODMAP content of your diet without compromising nutrient intake and variety simply by using smaller quantities of high FODMAP fruits and vegetables and increasing the quantities of low FODMAP ingredients. You may find that some classes of FODMAPs cause you more problems than other types. It is also probable that you will not get the same reaction on each occasion that you consume the same food items. There may be some days when you might consider a stricter low FODMAP diet such as before an important event or at times of greater stress.

Intolerance to bread and other foods containing wheat is common. This can be from the FODMAPs in whole wheat, allergy to yeast or wheat proteins, or coeliac disease. Coeliac disease is caused by an immune reaction to some of the proteins in the gluten and results in the gut lining becoming seriously damaged. Symptoms include pain, diarrhea, and malnutrition.  Gluten is present in wheat, barley and rye. Most individuals with coeliac disease can tolerate oats. Your doctor can order a blood test as an initial test for coeliac disease (NB It is important you are tested whilst still consuming gluten). Coeliac disease seems to becoming more common which may in part reflect greater community awareness and increased testing. We speculate that dietary factors may be responsible for some of the increase (see Gut Health page). Wheat products can be replaced with brown rice, oats, potatoes, sweet potatoes, brown rice pasta, buckwheat pasta, quinoa and other high fibre gluten free products.

The reputation of beans for increasing flatulence and gastrointestinal discomfort is overstated. One study of perceived flatulence found that most subjects reported no change when eating half a cup beans per day. But if this food group seems to cause you problems then there are low FODMAP options such as tofu and cooking methods that leach much of the FODMAPs out of the beans.

For more information on which foods to include in a low FODMAP diet see The Monash University Low FODMAP diet – Examples of low and high FODMAP foods. There is also an iPhone App which gives you a filter option for selecting which particular FODMAP classes you wish to restrict. This could be a very useful tool to use while shopping. Download from the App store, or see The Monash University Low FODMAP diet page. See also our Elimination diets page.

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