A detailed beginner's guide

Small carbohydrates called FODMAP are responsible for all sorts of digestive problems. A low-FODMAP diet can reverse these problems.

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Since what you eat can have a major effect on your body, digestive issues are incredibly common.

FODMAPs are types of carbohydrates found in certain foods, including wheat and beans.

Studies have shown strong links between FODMAPs and digestive symptoms like gas, bloating, stomach pain, diarrhea, and constipation.

Low-FODMAP diets can provide remarkable benefits for many people with common digestive disorders.

This article provides a detailed beginner’s guide to FODMAPs and low-FODMAP diets.

What are FODMAPs?

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.

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These are short-chain carbs that are resistant to digestion. Instead of being absorbed into your bloodstream, they reach the far end of your intestine where most of your gut bacteria reside.

Your gut bacteria then use these carbs for fuel, producing hydrogen gas and causing digestive symptoms in sensitive individuals.

FODMAPs also draw liquid into your intestine, which may cause diarrhea.

Although not everyone is sensitive to FODMAPs, this is very common among people with irritable bowel syndrome (IBS).

Common FODMAPs include:

Summary: FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which are small carbs that many people cannot digest — particularly those with irritable bowel syndrome.

What happens when you eat FODMAPs?

The majority of FODMAPs pass through most of your intestine unchanged. They’re completely resistant to digestion and are categorized as dietary fiber.

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But some carbs function like FODMAPs only in some individuals. These include lactose and fructose.

General sensitivity to these carbs also differs between people. Scientists believe that they contribute to digestive problems like IBS.

When FODMAPs reach your colon, they get fermented and used as fuel by gut bacteria.

The same happens when dietary fibers feed your friendly gut bacteria, which leads to various health benefits.

However, the friendly bacteria tend to produce methane, whereas the bacteria that feed on FODMAPs produce hydrogen, another type of gas, which may lead to gas, bloating, stomach cramps, pain, and constipation.

Many of these symptoms are caused by distention of the gut, which can also make your stomach look bigger.

FODMAPs are also osmotically active, which means that they can draw water into your intestine and contribute to diarrhea.

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Summary: In some individuals, FODMAPs are poorly digested, so they end up reaching the colon. They draw water into the intestine and get fermented by hydrogen-producing gut bacteria.

Benefits of a low-FODMAP diet

The low-FODMAP diet has mostly been studied in patients with irritable bowel syndrome (IBS).

This is a common digestive disorder that includes symptoms like gas, bloating, stomach cramps, diarrhea, and constipation.

About 14% of people in the US have IBS — most of them undiagnosed.

IBS has no well-defined cause, but it is well known that diet can have a significant effect. Stress can also be a major contributor.

According to some research, about 75% of people with IBS can benefit from a low-FODMAP diet.

In many cases, they experience major reductions in symptoms and impressive improvements in quality of life.

A low-FODMAP diet may also be beneficial for other functional gastrointestinal disorders (FGID) — a term that encompasses various digestive problems.

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In addition, some evidence suggests that it can be useful for people with inflammatory bowel diseases (IBD) like Crohn’s disease and ulcerative colitis.

If you are intolerant, then the benefits of a low-FODMAP diet may include:

It may also cause positive psychological benefits, as these digestive disturbances are known to cause stress and are strongly linked to mental disorders like anxiety and depression.

Summary: The low-FODMAP diet can improve symptoms and quality of life in many people with irritable bowel syndrome (IBS). It also reduces symptoms of various other digestive disorders.

Foods high in FODMAPs

Here is a list of some common foods and ingredients that are high in FODMAPs:

Foods you can eat on a Low-FODMAP diet

Keep in mind that the purpose of such a diet is not to completely eliminate FODMAPs — which is extremely difficult.

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Simply minimizing these types of carbs is considered sufficient to reduce digestive symptoms.

There is a wide variety of healthy and nutritious foods that you can eat on a low-FODMAP diet, including:

However, keep in mind that these lists are neither definitive nor exhaustive. Naturally, there are foods not listed here that are either high or low in FODMAPs.

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In addition, everyone is different. You may tolerate some foods on the list of foods to avoid — while noticing digestive symptoms from foods low in FODMAPs for other reasons.

How to do a low-FODMAP diet

Many commonly consumed foods are high in FODMAPs.

It’s generally recommended to completely eliminate all high-FODMAP foods for a few weeks.

This diet is unlikely to work if you only eliminate some high-FODMAP foods but not others.

If FODMAPs are the cause of your problems, then you may experience relief in as little as a few days.

After a few weeks, you can reintroduce some of these foods — one at a time. This allows you to determine which food causes your symptoms.

If you find that a certain type of food strongly upsets your digestion, you may want to permanently avoid it.

It can be difficult to get started and follow a low-FODMAP diet on your own. Therefore, it’s recommended to seek the advice of a doctor or dietitian who is trained in this area.

This may also help prevent unnecessary dietary restrictions, as certain tests can help determine whether you need to avoid the FODMAPs fructose and/or lactose.

Summary: It’s recommended to eliminate all high-FODMAP foods for a few weeks, then reintroduce some of them one at a time. It’s best to do this with the help of a qualified health professional.


FODMAPs are short-chain carbs that move through your intestines undigested.

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Many foods that contain FODMAPs are considered very healthy, and some FODMAPs function like healthy prebiotic fibers, supporting your friendly gut bacteria.

Therefore, people who can tolerate these types of carbs should not avoid them.

However, for people with FODMAP intolerance, foods high in these carbs may cause unpleasant digestive issues and should be eliminated or restricted.

If you frequently experience digestive upset that lowers your quality of life, FODMAPs should be on your list of top suspects.

Though a low-FODMAP diet may not eliminate all digestive problems, chances are high that it may lead to significant improvements.

Last updated on February 23, 2022, and last reviewed by an expert on November 25, 2021.

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