Low FODMAP Diets

Certain types of foods may cause digestive symptoms we commonly associate with Irritable Bowel Syndrome (IBS)  and gluten intolerance.

IBS is a real problem involving heightened sensitivity to digestive system distension or fullness, which can result in abdominal discomfort, nausea, bloating and diarrhea.

Celiac disease (also known as sprue) is a reaction to gluten (a wheat protein) resulting in progressive injury to the absorptive lining of the gut.  Around 1% of people have celiac disease. On the other hand, many more people report chronic abdominal discomfort, bloating or diarrhea which is alleviated by avoidance of gluten, even though they are proved not to have true celiac disease.

Two researchers at Monash University in Australia since 1999 (a dietician and a gastroenterologist) have found that certain types of foods may be fermented and/or poorly absorbed and could be responsible for these sort of non-specific, hard-to-pin-down symptoms.  The term FODMAP is now becoming more widely known as a result of their work.

FODMAP is acronymic for:

• Fermentable
• Oligosaccharides,
• Disaccharides,
• Monosaccharides
• And
• Polyols.

This handout (pdf) from the Canadian Digestive Health Foundation breaks this down, and further describes what these chemicals are very nicely.

Basically, some naturally occurring carbohydrates such as lactose (milk sugar), fructose (fruit sugar), the fructans in onion, garlic and wheat and galactans in beans can be fermented during digestion leading to discomfort, nausea and bloating. 

Additionally, some of these are not readily absorbed and can lead to water being drawn in to the colon before elimination resulting in diarrhea.  This latter is particularly true of synthetic sweetening polyols such as sorbitol or xylitol which are used to artificially sweeten foods, chewing gum and other products.

Mind you, we're talking about naturally-occurring constituents of common foods.  Some foods contain more of these than others.  For example, fructans are more abundant in wheat and rye than in rice or oats.  Similarly, apples and mangos contain more fructose than bananas or berries.

This pamphlet (pdf) from Stanford University Medical Center nicely shows within the FODMAP's, which foods to limit and which are okay.

If you feel that your digestive symptoms may be affected by dietary FODMAP's you can systematically limit dietary FODMAP's one group at a time for a few weeks to determine which group or groups you may wish to limit long-term.

Alternatively, you can limit all six groups at once.  If you notice improvement, you can then de-limit one group at a time to identify culprit groups.

Please note this is quite effective with limiting intake of culpable types of FODMAP's.  Absolute avoidance is not generally necessary.

(Also, we are just discussing food substances resulting in fermentation and poor absorption. 

Other digestive symptoms such as fever, weight loss, appetite loss, stringy bowel movements, blood or mucus in your bowel movements are warning signs of much more significant problems such as infections or cancers.  Please see me for such symptoms as soon as possible, and do not try to treat them with a reduced FODMAP diet.)