The Evidence Behind Using the Low FODMAP Diet for IBD

While there are several diets that have been popularized for use by people with inflammatory bowel disease (IBD), there is little in the way of research that can prove or disprove the ability of these diets to be helpful for IBD.

Whole and sliced tomatoes on a cutting board alongside a knife
tomato slices. Zachary Zirlin / EyeEm

The low FODMAP diet is becoming increasingly popular for people with digestive conditions, most notably for irritable bowel syndrome (IBS). FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, and in the low FODMAP diet, foods that contain these substances (which are types of carbohydrates and sugars) are limited.

This article will examine the low FODMAP diet and how it has been shown to affect IBD.

Diet and IBD: The Elephant in the Room

For people with digestive diseases such as IBD, diet is a big open question. Historically, there has not been much guidance, or even evidence, as to how people with IBD could eat in order to best nourish their bodies through a flare-up or even during remission.

There are anecdotal stories aplenty though: people who have tried a particular way of eating that has worked for them. Unfortunately, that's usually a result of trial and error and some of the diets are narrow to the point that they may lack necessary nutrients. However, people with IBD need to eat and it speaks to how awful these diseases are, and to the overwhelming lack of nutritional support, that patients are willing to try restrictive diets.

Fortunately, diet is now becoming a focus for research, and as scientists learn more, people with IBD will be able to get better diet guidelines. One such diet that's getting attention is the low FODMAP diet.

What's a FODMAP?

FODMAPs aren't exactly intuitive: it's not as if one can look at a food and figure out if it's low or high in FODMAPs. That's why foods are tested as to their FODMAP content and there's no shortage of lists where foods can be looked up.

However, knowing the components of the FODMAP acronym can be helpful for those who are using this diet. The basic premise is that certain components of foods are more likely to undergo fermentation and that some people may have fewer digestive symptoms if these foods are limited.

F Stands for Fermentable. The process of fermentation is when a food is broken down by yeasts, bacteria, or microorganisms. When this happens in the intestine, there are byproducts, including short-chain fatty acids and gases.

O Stands for Oligosaccharides. Oligosaccharides are carbohydrates which are composed of somewhere between 3 and 10 simple sugars linked together. Some oligosaccharides can't be digested in the humans intestine because the body doesn't produce the right enzyme (alpha-galactosidase) to digest it.

D Stands for Disaccharides. A disaccharide is a type of sugar that is actually two types of sugars linked together by what is called a glycosidic linkage. Disaccharides are also digested with the help of enzymes in the human body, but there are some people who may not make enough of some of these enzymes.

M Stands for Monosaccharides. A monosaccharide is a single sugar (that's where the "mono" comes in) that can't be broken down into smaller parts. During digestion, carbohydrates are broken down into monosaccharides, which are then taken up by the small intestine.

P Stands for Polyols. Polyols are sugar alcohols that are found in fruits and vegetables. There are also man-made polyols, such as artificial sweeteners like sorbitol and xylitol. Some polyols aren't fully digested, which is why they're lower in calories, because they pass through the body.

Will a Low FODMAP Diet Help?

There is currently no consensus on how much a low FODMAP diet would help people with IBD. There are some nuances to this, however, because IBD is not one disease but several diseases along a spectrum that have different characteristics. It is known that reducing FODMAPs will probably not help with inflammation caused by IBD. However, some people with IBD have symptoms even when they have no inflammation (and may be experiencing a form of remission).

The low FODMAP diet is getting the most attention for treating IBS. Because people with IBD can also have IBS, it's possible that a low FODMAP diet would help those with IBD who also have, or are suspected to have, IBS.

There is one small study that shows that low FODMAP helped people with IBD who have what's called "functional gut symptoms," which would include IBS-like symptoms such as gas, bloating, and diarrhea. The patients in this study were considered "stable" in regards to their IBD, but the researchers didn't do any particular testing to find out if there was IBD inflammation or other IBD-related problems occurring during the study. In this way, the results are somewhat limited, but it is a first step towards understanding if low FODMAP can help people with IBD who might also have functional digestive problem.

Another study looked at how a low FODMAP diet might help with symptoms for people who have had j-pouch (IPAA or ileal pouch-anal anastomosis) surgery. What they found is that people with a j-pouch had a tendency for carbohydrate malabsorption. In this very small study, patients that didn't have pouchitis (which is inflammation in the pouch) had fewer stools when FODMAPs were reduced.

Foods Considered Low FODMAP

Because a FODMAP isn't something that can be seen by looking at a food, having lists of foods is going to be helpful for anyone trying the low FODMAP diet. Below is a starter list that can help in understanding which foods might work with this diet:

  • Fruits: Bananas, blueberries, strawberries, raspberries, oranges, pineapple, grapes, cantaloupe, honeydew
  • Vegetables: Tomato, lettuce, kale, spinach, cucumber, carrots, green beans, bell peppers, zucchini, squash, eggplant
  • Grains and starches: Rice; quinoa; potatoes; oats; corn tortillas; gluten-free bread, pasta, crackers, cookies, and cereals
  • Dairy: Lactose-free milk, yogurt, cottage cheese, ice cream; hard or aged cheeses; butter; cream
  • Protein: Chicken, fish, turkey, beef, pork, eggs, firm tofu, peanut or almond butter, seeds, some nuts, small portions of canned chickpeas and lentils

Foods Considered High FODMAP

All high FODMAP foods aren't the same: some are going to have higher levels than others. Working with a dietitian can help with incorporating any of the higher FODMAP foods in the diet. Some people may be able to tolerate higher FODMAP foods in small amounts while others will not. In general, some of the higher FODMAP foods include:

  • Fruits: Apples, mangos, pears, peaches, watermelon
  • Grains: Wheat, rye, barley
  • Lactose: Milk, ice cream, yogurt
  • Plant-based milks: Soy, rice, oat
  • Legumes: Baked beans, soybeans, black beans
  • Sweeteners: Agave, honey, high fructose corn syrup
  • Vegetables: Asparagus, cauliflower, garlic, onion, snap peas

Is Low FODMAP Too Restrictive for IBD?

IBD affects digestion and some people with IBD don't get enough nutrients, either because of being unable to eat nutrient-dense foods or because the small intestine isn't absorbing vitamins and minerals the way it should.

One concern is that a low FODMAP diet would cut out various foods and wind up being too restrictive, causing even more nutritional problems. One study showed that people with IBD might already be eating low FODMAP. In this case, the researchers recommend working with a dietitian to be the best way to try the low FODMAP diet and still get all the needed vitamins and minerals. In addition, the low FODMAP diet isn't meant to be a long-term diet, but instead is part of an overall diet plan.

Adopting a low FODMAP diet isn't free from trial and error, either, however. Every person is going to have a different range of FODMAPs that are going to be tolerable on a daily basis. This needs to be coupled with lifestyle and taste: it does no good to have a low FODMAP diet plan that contains foods that aren't liked, can't be easily obtained, or are difficult to prepare and cook. It should be noted that in most low FODMAP studies, participants did not find the diet difficult to follow or restrictive, which is probably due to the wide variety of foods that are classified as low FODMAP.

A Word From Verywell

We still don't know enough about how beneficial the low FODMAP diet is for people who have IBD. There have been some studies, but they haven't been big enough or comprehensive enough to make any decisions yet.

For people with IBD who are doing well in terms of inflammation or other IBD markers but who still have symptoms, the low FODMAP diet may be helpful. It could help in reducing the IBS-like symptoms that are happening when the IBD is being controlled.

There are many online resources available to help in finding low FODMAP foods that will fit in with an IBD-friendly diet plan. However, it's important that a dietitian be consulted in crafting the right diet.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.