The Lowdown on FODMAPS

When you have problems with digestion leading to bloating, constipation, urgency, or any combination it is common to look for the inciting cause in our food.  Any gut complaint can lead to poor performance in the gym, lack of nutrient availability, or even an urgency to leave the track to hit the toilet. This especially becomes an issue at the time of contest readiness leading to a desire to eliminate many healthy foods.  Though, we must take caution as many people start eliminating entire food groups to the extreme of nutritional deficiencies.

Irritable bowel syndrome (IBS) is a common problem that can lead to a multitude of gastrointestinal (GI) complaints, as above, without certain etiology.  It may be from hyperactivity of the GI tract, altered microbial colonies, increased fermentation, food intolerance, or dysfunction in the gut-brain axis.  In attempts to battle food intolerance and increased fermentation, scientists are trying to combat this disease with a low-FODMAP diet1.

F.O.D.M.A.P.s are Fermentable Oligo-, Di-, and Monosaccharides And Polyols.  That is a mouthful.  In brief, these are short chains of carbohydrates or sugars and their related sugar alcohols (polyols).  The most problematic are the short chains of fructose and galactose, fructose and galactose themselves, lactose (glucose and galactose), and the sugar alcohols (sorbitol, mannitol, etc.).  These can be fermented in the colon by gut bacteria to produce bloating and GI upset because they are poorly digested or poorly absorbed in the small intestine.

One of the largest problems in the American diet is the prevalence of high-fructose corn syrup.  When large amounts of fructose are consumed with glucose, the glucose is more easily absorbed and the fructose ends up in the colon to be fermented.  Studies suggest that up to 40% of us may have fructose malabsorption1.  The prevalence of lactose intolerance, from a lack of lactase to digest it, is quite high and can result in severe GI upset.

Naturally occurring chains of galactose are found in lentils, legumes, and beans which are not digestible in the small intestine and are thus digested by gut bacteria.  However, the short-chain fatty acids that the bacteria produce from these are very important to our metabolic health, the health of our intestinal lining, and possible prevention of cancer.

The polyols or sugar alcohols are often added to the diet as sugar substitutes, but are also found naturally in apples and pears (sorbitol) and mushrooms and cauliflower (mannitol).  These are not well absorbed by the GI tract as they have no transporters.  They exert a strong “osmotic effect” drawing water into the colon while also being fermented by gut bacteria; a double whammy.

Unfortunately, FODMAPs are present in a lot of the foods we eat.  Studies show that reducing FODMAPs in a diet can improve symptoms like those found in irritable bowel syndrome1.  However, these diets can be very restrictive and even result in nutritional deficiencies.  Further, the lack of digestible carbohydrate (pre-biotics) for our gut bacteria can result in a loss of healthy short-chain fatty acids and growth of unhealthy microbial species.

One way around this, is to be systematic in your elimination of FODMAP containing foods.  First, start by removing the most common players in GI intolerance, the polyols.  Avoid the processed foods where these are added like chewing gums and the sugary pulpy fruits like apples, pears, and peaches.  Second, remove the foods and drinks containing high-fructose corn syrup, evaporated cane juice, or honey.  High fructose sports drinks or energy packs can be very upsetting to the stomach.  Third, cut back on your quantities of wheat, rye, and barley.  Even though these contain relatively lower amounts of FODMAPs they are often eaten in excessive quantities.  When in doubt about the condition of your gut, see a board certified gastroenterologist.

Low FODMAP Foods:

Proteins: beef, fish, chicken, eggs

Dairy: Mozzarella or hard cheeses (often have lactose digested out)

Grains: Gluten-free flowers, quinoa, rice, oats

Veggies: Carrots, yams, spinach, kale.

High FODMAP Foods:

Proteins: Beans, lentils, cashews

Dairy: Milk, yogurt

Grains: Wheat, Barley, Rye (only because eaten in quantity)

Veggies: Cauliflower, broccoli, onions, cabbage



Khan MA, et al. Low-FODMAP Diet for Irritable Bowel Syndrome: Is It Ready for Prime Time? Dig Dis Sci. 2015 May;60(5):1169-77