What Is the Low-FODMAP Diet?

low-FODMAP foods on a marble surface

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The low-FODMAP diet is based on the theory that limiting high-FODMAP foods reduces uncomfortable digestive symptoms, such as abdominal pain, bloating, gas, diarrhea, and constipation. Research suggests this diet may help patients with irritable bowel syndrome (IBS) and Crohn’s disease.

FODMAP refers to a group of short-chain carbohydrates that contribute to digestive problems. They’re found in many common foods, including yogurt, wheat, beans, and certain fruits and vegetables. Followers of the low-FODMAP diet avoid these foods and stick to a list of low-FODMAP foods to prevent flare-ups.

It’s a form of an elimination diet, but a low-FODMAP diet is still high in nutrient-dense foods.

What Experts Say

“The Low-FODMAP diet reduces certain carbohydrates to help relieve symptoms of IBS. There is quality research on this diet’s effectiveness. Because it involves avoiding certain foods, experts agree it’s helpful to work with a professional to maximize choices for long-term use.” —Willow Jarosh, MS, RD 

Background

The FODMAP theory was introduced in 2005 by an Australian research team led by Peter Gibson and Susan Shepherd. They published their hypothesis that excessive FODMAPs contribute to increased susceptibility to Crohn’s disease, which is an inflammatory bowel disease (IBD). 

What Is a FODMAP?

FODMAP stands for fermentable oligo-, di-, mono-saccharides and polyols. These are short-chain carbohydrates that draw water into the digestive tract, which can lead to bloating and sensitivity. Eating a large volume of high-FODMAP foods can even cause them to ferment in the gut, contributing to further symptoms.

By taking a look at the increased intake of FODMAPs in Western societies and the development of Crohn’s disease, Gibson and Shepherd were able to support their hypothesis. They suggest a low-FODMAP diet to prevent and manage Crohn’s disease. Upon further research, the diet has been heavily associated with a reduction in IBS and other forms of IBD.

The diet was popularized shortly after the initial study and has since been heavily researched and accepted as an effective treatment for IBS. 

How It Works

The low-FODMAP diet consists of very specific foods to avoid and foods to eat. With each food group, some foods are considered high in FODMAPs while others are low. For example, apples and bananas are both fruits, but only the latter is considered low-FODMAP.

Some compliant foods on the low-FODMAP diet include:

Eating a low FODMAP diet is a little more complicated than simply avoiding certain foods. This is because some foods contain higher levels of FODMAPs when they are consumed in larger portions. Therefore, the type of food and amount of food are important.

For example, followers can only consume ⅛ of an avocado at a time, and certain nuts should be limited to 10. Similarly, coconut milk must be limited to ½ cup and bulgar should be limited to ¼ cup cooked. Artificial sweeteners are allowed on the diet, but sugar alcohols are not. Sugar alcohols typically end in -ol. 

The list of low-FODMAP foods is extensive, but so is that of high-FODMAP foods that must be avoided. Some examples include watermelon, honey, high fructose corn syrup, most dairy products, cauliflower, garlic, onions, asparagus, legumes, barley, rye, soy milk, pasta, etc.

Pros and Cons

Many studies confirm the benefits of a low-FODMAP diet. In a 2011 study, 76% of people with IBS who followed a low-FODMAP diet reported satisfaction with their symptom management while on the diet. A low-FODMAP diet may also be beneficial for patients with other gastrointestinal disorders. Research suggests that the digestive benefits of a low-FODMAP diet include less abdominal pain, gas, bloating, diarrhea and constipation.

With so many non-compliant foods, a low-FODMAP diet can be difficult to follow. Some experts believe that a low-FODMAP diet should only be done short-term and with the help of a professional. The diet is also restrictive, and followers must consume a variety of compliant foods to prevent nutritional deficiencies. Digestive problems may also resume once followers return to a diet higher in FODMAPs.

Common Myths and Questions

The low-FODMAP diet can be complicated and difficult to understand. As such, it’s easy to spread or believe misinformation. Here are some common myths about the low-FODMAP diet and the facts that set the record straight.

Myth: You can’t eat animal products on a low-FODMAP diet.

Some animal products are high-FODMAP foods, but many animal products are allowed on the diet. Compliant animal products include meat, fish, eggs, and very few dairy products. Lactose-free dairy products are allowed as well as the following cheeses: Brie, camembert, mozzarella, and Parmesan.

Myth: The low-FODMAP diet is a long-term lifestyle change.

The low-FODMAP is designed to be temporary. It consists of several phases that may differ but usually consist of elimination, re-introduction, and maintenance. The elimination phase is the most restrictive and usually lasts for two to six weeks. Then, high-FODMAP foods will be slowly re-introduced to identify which foods trigger digestive symptoms. Tolerable foods can be incorporated into your long-term foods while triggering foods should be consumed in moderation or avoided altogether.

Myth: You can’t eat gluten on a low-FODMAP diet.

The low-FODMAP diet is not completely gluten-free, though gluten-free foods are recommended. Some gluten-containing foods are high in FODMAPs while others are lower. Bulgar and spelt are low-FODMAP foods that contain gluten.

How It Compares

The low-FODMAP diet is both similar and dissimilar to many popular diets. Here’s how it compares:

  • Temporarily removes certain foods to determine food sensitivities that cause undesirable symptoms
  • Allows some high-FODMAP foods like certain grains, legumes, fruits and vegetables
  • Recommended for people with a milk allergy or lactose intolerance
  • Both this diet and the low-FODMAP diet reduce or eliminate foods containing lactose and high-fat sources of dairy
  • Strict grain-free, lactose-free and sucrose-free diet for people with Crohn’s disease, ulcerative colitis, celiac disease, IBD and IBS
  • Not as researched as the low-FODMAP diet
  • Has a different set of restrictions (e.g. no starches, seeds, grains, etc.) but a wider selection of fruits and vegetables

Getting Started

It’s strongly recommended to follow the low-FODMAP diet under the supervision of a health professional. The founders at Monash University recommend consulting with a dietician to create a low-FODMAP plan for you.

Once you’ve consulted with a professional, you can get started by shopping for low-FODMAP groceries and getting creative with compliant recipes. Though the most restrictive part of the low-FODMAP diet lasts up to 6 weeks, you may begin experiencing fewer symptoms in just a couple of weeks.

A Word From Verywell

Gastrointestinal health problems affect millions of people. The low-FODMAP diet has become one of the go-to therapies for people experiencing uncomfortable digestive symptoms, especially related to IBS and IBD. 

Because the low-FODMAP diet is short-term, it’s not a long-term solution to your digestive symptoms. Though there is no cure for some digestive conditions, the low-FODMAP diet is one method of managing your symptoms and preventing flare-ups.

This diet may be used as a temporary program to identify foods that trigger discomfort. Once you’ve completed the diet, you may be able to pinpoint which high-FODMAP foods are tolerable or triggering for you. This will allow you to make food choices that encourage you to feel your best.

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