What Exactly Are FODMAPs? (2024)

Perhaps it was a dinner with asparagus and apple pie that left you feeling bloated and miserable. Or maybe it was that pasta salad at lunch, the one that made you wonder if it was something you ate. It likely is.

Foods that cause gastrointestinal (GI) distress often have one thing in common: they're FODMAPs. These are short-chain carbohydrates (sugars) found in foods known to cause symptoms in people with irritable bowel syndrome (IBS) and other GI disorders.

This article explains what FODMAPs are and why they can cause such distress. It also lists some of the foods you may want to avoid.

What Does FODMAP Mean?

FODMAP is an acronym that stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Some of these can't be broken down before they make it to the gut because they are fibers (i.e. we don't produce the enzyme that breaks down galacto-oligosaccharides until it enters the large intestines/gut).

Then nutrients are not absorbed well, and the sugars stay in the gut. They quickly ferment and pull water into the digestive tract.

What FODMAPs Do

When the sugars from FODMAP foods ferment in the digestive tract, they cause discomfort. These symptoms may include:

• Bloating
• Gas
• Abdominal pain
• Constipation
• Watery diarrhea

You may feel these symptoms in as little as 30 minutes because gas and extra water cause the abdomen to swell. In some cases, you may feel an urgent need to move your bowels.

Types of FODMAP Sugars

FODMAP foods cause GI symptoms because of the sugars they contain, but there is more than one kind of sugar at work. What happens chemically in the GI tract depends on the type of FODMAP. Here are two examples.

Fructose

Fructose is found in fruits, vegetables, and many packaged foods. It also is a chemical component of table sugar, known as sucrose. Two proteins in the small intestine are responsible for helping the body to absorb fructose.

One is limited in its capacity to do so, and that's on the basis of its normal function. The other one is more efficient in helping the body to absorb nutrients, but not in the absence of sugar in its glucose form. Fructose is absorbed pretty well when there is more glucose in the mix with it.

But when there is more fructose than glucose, neither of these proteins are fully at work. That means the fructose doesn't get absorbed well and GI symptoms may start to appear.

Polyols

Like fructose, polyols are found in fruits and other natural foods, including mushrooms—a top FODMAP problem. They may be added to processed foods during manufacturing. They're also common in sweeteners and sugar substitutes that people with diabetes, or those seeking to lose weight, turn to instead of table sugar. However, polyols are not well absorbed in the small intestine.

When they reach the large intestine, they may cross the internal lining tissue through pores. Depending on the size of the pores, which may be changed in the presence of some diseases, it can be more difficult to absorb polyols. They begin to ferment and are also osmotic - meaning they bring water with them. This may lead to watery diarrhea.

FODMAPs and Stress

There are other reasons for why people develop IBS, but stress may play an important role. There also are differences in how FODMAP foods affect people who have IBS.

Taking Control of Your Diet

One frustrating thing about FODMAPs is that it's not always clear which foods cause your symptoms. The FODMAP challenge diet is one way to find out which foods to eliminate.

First, you need to eliminate all FODMAPS entirely for at least two weeks, though three is preferred. After two weeks, you may begin to reintroduce one FODMAP food at a time. If the food is going to cause symptoms, it will happen fairly quickly. Within a few weeks, you should know which FODMAPs, and in what amount, trigger your symptoms. These are foods you should avoid.

Any FODMAP foods that don’t cause symptoms remain a part of a nutritious, balanced diet.There is a caution about fruit, though. Some fruits may contribute to GI distress because of their mixed fructose-glucose content. People with IBS may need to eat them carefully in smaller amounts. It's also a good idea to avoid processed foods because of FODMAPs added into the ingredients.

Keep in mind that people may tolerate one FODMAP group and not the other ,so it's very individualized. Also, it's cumulative, so no one has to avoid any food in its entirety unless there is an allergy. A registered dietician (RD) who specializes in gastrointestinal nutrition can help identify triggers for a short term elimination diet.

Summary

FODMAP foods contain sugars and polyols known to cause GI symptoms, like gas and diarrhea. They may be poorly absorbed in the GI tract and begin to ferment in the intestines. This is especially true for people with IBS and other GI disorders. One way to limit these problems is to identify specific foods that cause symptoms.

Knowing which foods are FODMAPs is one place to begin. Once you've adjusted your diet, you can continue to eat the other healthy FODMAP foods you enjoy. Eating a wide variety of these foods also helps to build up intestinal bacteriathat keep your gut healthy.

A Word From Verywell

If you want to start changing your diet to reduce the impact of FODMAP foods, consider speaking with your healthcare provider or a dietitian. They can guide you in the process to ensure the best results.