Irritable Bowel Syndrome: What to Know About a Low FODMAP Diet

Rachel Despres

Published on July 27, 2017 Updated on April 20, 2021

Health Check Certified By: Julie Ching, MS, RDN, CDE

Those with digestion issues such as Irritable Bowel Syndrome (IBS) know all too well the discomfort of abdominal pain, intestinal gas and bloating that can occur after eating certain foods.

Thankfully, the recently popularized low FODMAP diet has proven effective for reducing these symptoms. In fact, it is increasingly being accepted and recommended as a dietary therapy for IBS by physicians. Before giving the low FODMAP diet a try, here are six important things to know.

What Are FODMAPs?

FODMAP is an acronym used to describe certain carbohydrates—specifically the short-chain variety—found in foods. According to FodmapFriendly.com, it stands for:

Fermentable

Oligosaccharides

Disaccharides

Monosaccharides

and

Polyols

In those who suffer from digestion problems like IBS, the International Foundation for Functional Gastrointestinal Disorders says FODMAPs “are poorly absorbed in the small intestine and rapidly fermented by bacteria in the gut.” The gas produced by these bacteria is a primary cause of the disorder’s symptoms.

Common FODMAPs

FODMAPs are found in many day-to-day foods, so it’s important to be mindful of what to avoid while on the diet. Fructose is one FODMAP carbohydrate to stay away from, and is commonly found in things like fruits, vegetables and honey. Lactose, from dairy products, also needs to be eliminated. So, too, should sources of fructans like wheat, onions and garlic.

It’s recommended that those on a low FODMAP diet also refrain from eating legumes like beans, lentils and soy, which contain carbohydrates called galactans. Polyols—from stone fruits like avocado, cherries and peaches, as well as any sweeteners containing sorbitol, mannitol, xylitol or maltitol—should be avoided as well.

Who Is The Diet For?

A low FODMAP diet is primarily used to help those with IBS, but it can also be beneficial for people with functional gastrointestinal disorder and certain autoimmune diseases like rheumatoid arthritis, multiple sclerosis, eczema and fibromyalgia.

While most people are able to easily digest FODMAPs, individuals with these conditions can be particularly sensitive to them. WebMD says this is because “FODMAPs draw water into your digestive tract, which could make you bloated. If you eat too much of them, they can hang around in your gut and ferment.” A low FODMAP diet will help to ease these symptoms by temporarily eliminating trigger foods until a cause can be identified.

How It Works

The first phase of the FODMAP diet, known as the elimination phase, is an approximately three to eight week time period during which all FODMAPs must be excluded from the diet.

Following the FODMAP diet is only intended to be a temporary remedy for uncomfortable symptoms such as gas, bloating and diarrhea, so after the elimination phase is complete, the reintroduction or re-challenge phase begins. During this second phase, each FODMAP is reintroduced into the diet one at a time in order to identify what is causing the irritation.

Common Pitfalls

As with many diets, there are common low FODMAP diet pitfalls that can hinder its effectiveness. One such pitfall, according to the International Foundation for Functional Gastrointestinal Disorders, is over-limiting your diet. To avoid lactose, for instance, many people will remove all dairy products from their diet, but this is unnecessary. “You can continue to use low-lactose milk products such as aged cheeses and lactose-free yogurt on a low FODMAP diet,” the source says, unless the person is vegan or has an allergy to milk.

Another common pitfall is not getting enough fiber while on the low FODMAP diet. This tends to happen as a result of eliminating so many foods from the diet, but fiber is important for gut health. Seek out low FODMAP fibers—which can be found in certain fruits, vegetables and grains—as the source says they are “fermented more slowly and are less likely to disrupt fluid balance in the gut.”

Low FODMAP Diet for IBS

Although a low FODMAP diet has helped those with conditions like functional gastrointestinal disorder, multiple sclerosis and fibromyalgia, most of the research to-date has been on patients of IBS.

In a 2014 study, for instance, 30 people with IBS were put on a low FODMAP diet for 21 days. During this time, participants saw a 50-percent decrease in symptoms such as bloating, abdominal pain and gas. A low FODMAP diet may not be appropriate for everyone with IBS, however, so it’s important to speak to a physician and find a registered dietitian who can help you manage the elimination diet prior to trying it.