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Low FODMAP Diet

What Is It, Foods To Eat, and More

Author:Anna Hernández, MD

Editors:Alyssa Haag,Józia McGowan, DO,Kelsey LaFayette, DNP, RN, FNP-C

Illustrator:Jessica Reynolds, MS

Copyeditor:Stacy Johnson, LMSW


What are FODMAPs?

Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, or FODMAPs, are short-chain carbohydrates that are poorly absorbed in the gastrointestinal tract

FODMAPs include oligosaccharides, like fructans and galactooligosaccharides (GOS); disaccharides, like lactose; monosaccharides, like fructose; and polyols or sugar alcohols, like sorbitol, mannitol, xylitol, and maltitol. FODMAPs are naturally present in the human diet and play an essential role in maintaining a healthy gut flora; however, because they are not easily absorbed in the gastrointestinal tract, they can trigger symptoms like abdominal pain, bloating, and gas in individuals with sensitive GI tracts, like those with irritable bowel syndrome (IBS). 

Inflamed and bloated intestines from high FODMAP foods.

What is irritable bowel syndrome (IBS)?

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by recurrent abdominal pain and atypical bowel motility that leads to constipation, diarrhea, or a combination of the two. The underlying cause of IBS is not entirely understood. Still, it appears to be related to visceral hypersensitivity when the sensory receptors in the gastrointestinal walls have an extreme response to stimuli like stretching during and after a meal. Most individuals with irritable bowel syndrome associate their symptoms with eating and may try to ease them by avoiding certain foods, like FODMAPs, or using elimination diets. 

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What is a low FODMAP diet?

A low FODMAP diet  can involve taking multiple foods out of one’s diet, followed by a period of reintroduction of these foods to determine the individual’s food sensitivities

How does a low FODMAP diet improve gastrointestinal symptoms?

A low FODMAP diet reduces gastrointestinal symptoms by decreasing the effect of FODMAPs on the gastrointestinal tract. FODMAPs are highly fermentable short-chain carbohydrates that are poorly absorbed in the gastrointestinal tract and act as osmotically-active solutes that draw water into the intestinal lumen. Excess water in the intestinal lumen may cause the smooth muscle lining of the intestinal walls to spasm and lead to diarrhea if the excess water is not reabsorbed into the body. When the unabsorbed short-chain carbohydrates reach the colon, they are metabolized and fermented by gastrointestinal bacteria, producing gas. The gas produced may further stretch the walls of the gastrointestinal lining, which can trigger abdominal bloating, cramping, and pain. 

Although a low FODMAP diet may help improve IBS symptoms, following a low FODMAP diet in the long term can harm the gut microbiota. Therefore, the elimination phase is typically only advised for a period of six to eight weeks. While the low FODMAP diet has been studied primarily on people with IBS, it is often recommended for those with other gastrointestinal disorders, including inflammatory bowel disease, celiac disease, and small intestinal bacterial overgrowth (SIBO). Because a low FODMAP diet involves eliminating many foods, individuals may want to seek guidance from a trained doctor or dietitian to avoid unnecessary over-restriction. 

What foods are best on a low FODMAP diet?

The best foods to eat on a low FODMAP diet include high-protein foods, like meat, fish, poultry, firm tofu, tempeh, or eggs; and fatty foods like oil, butter, and hard cheeses (e.g., cheddar, gruyere, Emmental, parmesan). Kefir and lactose-free dairy products and grains like quinoa, rice, cornmeal, and gluten-free products may also be consumed. 

Low FODMAP fruits, such as unripe bananas, blueberries, grapefruit, grapes, lemons, oranges, pineapples, and berries, may be eaten depending on the individual’s tolerance. In general, fresh or frozen fruit is better tolerated than canned fruit, dried fruit, and fruit juices. Low FODMAP sweeteners include granulated sugar, brown sugar, corn syrup, aspartame, saccharin, sucralose, and stevia. Vegetables with lower FODMAP content include carrots, celery, cucumber, eggplant, green beans, leafy greens, pumpkin, red bell peppers, squash, potatoes, and zucchini. 

What foods should be avoided on a low FODMAP diet?

A list of foods that should be avoided on a low FODMAP diet includes most fruits and vegetables, lactose-based dairy products, grains, beans, and legumes. 

Specifically, stone fruits, like apricots, cherries, mangoes, nectarines, peaches, plums, apples, pears, watermelons, and lychees, have a high FODMAP content. Vegetables high in FODMAPs include artichokes, asparagus, beets, broccoli, brussels sprouts, cabbage, cauliflower, garlic, green bell peppers, and sweet corn. In addition, milk, yogurt, ice cream, cottage cheese, and ricotta cheese should also be avoided due to their high lactose content. Honey, agave, and artificial sweeteners may contain sugar alcohols that are not well absorbed and should also be avoided. Finally, grains like wheat, barley, rye, and most legumes and nuts are generally not recommended on a low FODMAP diet. 

What are the most important facts to know about a low FODMAP diet?

A low FODMAP diet is an elimination diet that restricts the intake of Fermentable, Oligo-, Di-, Mono-saccharides, and Polyols, which are a type of carbohydrates that are thought to trigger gastrointestinal symptoms such as abdominal bloating, pain, and changes in bowel habits. The low FODMAP diet is especially recommended in individuals with irritable bowel syndrome (IBS) though it may be part of treating other gastrointestinal disorders. Because it is a very restrictive diet, it should be provided by a trained doctor or dietitian to avoid nutritional deficiencies and unnecessary over-restriction. 

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Related links

Irritable bowel syndrome
Carbohydrates and sugars
Gastrointestinal system anatomy and physiology

Resources for research and reference

Catassi, G., Lionetti, E., Gatti, S., & Catassi, C. (2017). The low FODMAP diet: Many question marks for a catchy acronym. Nutrients, 9(3), 292. https://doi.org/10.3390/nu9030292

Gibson, P. R., & Shepherd, S. J. (2010). Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology, 25(2), 252–258. https://doi.org/10.1111/j.1440-1746.2009.06149.x

Low-FODMAP diet. (2016, August 3). American College of Gastroenterology. https://gi.org/topics/low-fodmap-diet/

Treatment of irritable bowel syndrome in adults. (n.d.). Uptodate.com. Retrieved November 4, 2022, from https://www.uptodate.com/contents/treatment-of-irritable-bowel-syndrome-in-adults