FODMAP Diet: What To Eat
What are FODMAP’s?
FODMAP is an acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. These are 4 different categories of poorly absorbed carbohydrates and sugars that are found in a variety of foods like fruits, vegetables, grains and milk. Oligosaccharides are compounds like fructans (onions, wheat) and galacto-oligosaccharides (legumes). An example of a disaccharide is lactose found in milk. Fructose, which is found in many fruits, particularly apples and watermelon are monosaccharides. Polyols can be found in certain fruit like apples and prunes, but are also in sweeteners (xylitol, maltitol, sorbitol) found in many sugar-free products. When these non-absorbed sugars pass through the small intestine and enter into the colon, they are fermented by the bacteria there. This fermentation process produces gas, which causes bloating and pain, and also causes water to move in and out of the colon, leading to diarrhea, constipation or both. FODMAP foods appear to cause significant side effects for some people who have underlying gastrointestinal issues, like irritable bowel syndrome or small intestinal bacterial overgrowth.
Why some people may want to avoid FODMAP’s
Eliminating FODMAPS from the diet can be helpful for patients who have irritable bowel syndrome (IBS) and/or small intestinal bacterial overgrowth (SIBO). These two conditions overlap and can often be indistinguishable in some patients. In irritable bowel syndrome, patients feel the distention in the walls of the intestines from gas that is produced by the bacteria fermenting the FODMAP sugars. This leads to significant discomfort and pain for these patients. Many of these patients also have bouts of either diarrhea or constipation or both, usually due to the movement of water in and out of the colon from the effects of these sugars. Avoiding FODMAP’s can decrease these symptoms in many patients. Typically, a FODMAP diet is initiated for 8 weeks and then patients are encouraged to try adding back one food at a time to see if they can isolate which foods causes the most symptoms. If that food is found to be problematic, then it should be eliminated long term.
The other condition that a FODMAP diet can be very helpful for is small intestinal bacterial overgrowth (SIBO), which is an increase in the number of bacteria that are typically found in the large intestine in the small intestine. The small intestine should contain very few bacteria if any. When these bacteria migrate up from the large intestine into the small intestine, they cause a variety of symptoms such as bloating, gas, belching, diarrhea, constipation, anemia and weight loss. These bacteria in the small intestines disrupt normal digestion and absorption of nutrients and ferment carbohydrates, like the ones found in FODMAP foods. These bacteria can produce two different gases, hydrogen and/or methane. When there is a lot of hydrogen gas produced in the small intestine, it is likely to cause diarrhea, whereas methane is more likely to cause constipation. Eliminating FODMAP’s can be helpful in decreasing the amount of gas produced by these bacteria. The diet alone might not be enough to eliminate these bacteria, but it can control the symptoms considerably.
Risks associated with going on a low-FODMAP diet
There are various opinions in this area. Some believe that eliminating FODMAP’s is very restrictive and should not be followed lifelong. The concern is that this could lead to nutritional deficiencies. They suggest that after a period of elimination, the foods should be reintroduced one at a time and the assumption is that patients will become more tolerant of those foods with time. The problem is that many patients continue to have the underlying issue, like persistent SIBO, that predispose them to having difficulty tolerating FODMAP foods, sometimes for life. Since there are plenty of healthy, nutrient dense food options that are low in FODMAP’s, the diet is perfectly safe to be continued indefinitely, especially if a patient feels that the diet is helpful for them.
The best and worst FODMAP foods
There appears to be considerable inconsistencies between various lists that report high and low FODMAP foods. A food may be listed as low FODMAP on one list, but high on another and this can be very confusing. In this case, the individual patient will need to determine how they react to that particular food.
The following list of foods by category is considered highest in FODMAP (the worst foods) by most authorities:
Vegetables- artichokes, asparagus, onions, mushrooms
Fruit- apples, dried fruit, cherries, peaches, watermelon
Dairy- cow’s milk, yogurt, ice cream
Protein sources- legumes and pulses: baked beans, black-eyed peas, butter beans, chickpeas, kidney beans, lentils, soybeans, split peas, processed meats like sausages
Grains- cereal and baked goods made wheat, barley, and rye
Sweeteners- high fructose corn syrup, honey, xylitol, maltitol, sorbitol
Nuts and seeds- cashews and pistachios
The foods lower in FODMAP:
Vegetables- zucchini, cucumber, bok choy, potato
Fruit- strawberries, kiwi, oranges
Dairy- lactose-free milk, hard cheeses, almond milk
Protein sources- eggs, poultry, plain meat, seafood
Bread and cereals- rice, quinoa
Sweeteners- pure stevia, maple syrup, monk fruit
Nuts and seeds- macadamia, pumpkin seeds, walnuts
For more information on FODMAP Diets, click here to read my full interview in Eat this Not That