FODMAP Diet: Everything You Need to Know

Medically reviewed by Karina Tolentino, RD

FODMAPs are a type of carbohydrate that can resist digestion. "FODMAP" stands for "fermentable oligosaccharides, disaccharides, monosaccharides, and polyols." A low-FODMAP diet helps people with digestive issues identify which foods are triggers for them, or they may just benefit overall by reducing those foods in their diet.

This article covers everything you need to know about the low-FODMAP diet, from what it is to which conditions may benefit from it.

What Are FODMAPs?

FODMAPs are a group of sugars (types of carbohydrates) that are not completely absorbed in the gut. In some people, this inability of FODMAPs to be absorbed can trigger digestive upset and other symptoms, particularly in people with irritable bowel syndrome (IBS).

FODMAPs are naturally found in numerous foods and beverages, including some fruits, vegetables, grains, nuts, legumes, lentils, dairy products, and manufactured foods.

What Happens When You Eat FODMAPs?

As FODMAPs slowly move through the digestive tract, they attract water. When they reach the large intestine (colon), bacteria ferment the FODMAPs, producing gas as a byproduct. The extra water and gas can push on the intestinal wall, expanding and stretching the large intestine.

Most people don’t experience noticeable symptoms when this happens. However, in some people with sensitive guts, it can cause an exaggerated response, resulting in pain and discomfort. Symptoms include:

• Abdominal pain

• Bloating

• Diarrhea and/or constipation

• Distension

• Fatigue

• Flatulence (passing gas)
  

What’s the Low-FODMAP Diet?

The low-FODMAP diet is an eating plan that reduces the amount of foods you eat that contain FODMAPs. People with IBS often follow it to help reduce or resolve their symptoms. It has been shown to help improve symptoms in 75% of people with IBS.

The low-FODMAP diet has three phases, as follows:

• Phase one: You reduce the amount of all FODMAP categories for a limited time.

• Phase two: You slowly reintroduce one category at a time to see how your body reacts to the different foods.

• Phase three: You and your dietitian personalize a long-term low-FODMAP diet based on what you can and cannot tolerate.

You do not need to eliminate all FODMAPs from your diet forever. Instead, you reduce the quantity of FODMAP triggers in your diet, allowing you to experience fewer symptoms and feel your best.

Each person has their own individual triggers, so trialing the low-FODMAP diet can help you identify which foods are causing your symptoms and in what amounts.

Why Are FODMAPs Difficult to Digest?

FODMAPs are a type of fermentable short-chain carbohydrate that are resistant to digestion in the small intestine.

The chains in the carbohydrates cannot be broken down and absorbed in the small intestine. Because they aren’t absorbed or digested, the small intestine draws in extra water to help move the FODMAPs along the digestive tract to the large intestine.

When these undigested carbohydrates reach the large intestine, they act as a source of food for gut bacteria. These bacteria feed off the short-chain carbohydrates and end up producing gases and fatty acids as byproducts.

Are FODMAPs Bad for Everyone?

The short answer is no. Most people are able to consume FODMAPs without any symptoms.

Our digestive systems are designed to process nondigestible carbohydrates and fibers in a certain way. Fiber and other nondigestible carbohydrates play an important role in digestive health, acting as prebiotics, or food for the good bacteria in the gut.

However, some people with a sensitive gut respond differently to the processing of these carbohydrates and their byproducts, resulting in unpleasant symptoms and affecting their quality of life.

Who May Benefit From a Low-FODMAP Diet?

The low-FODMAP diet is designed for people with medically diagnosed IBS. The low-FODMAP diet is a temporary but very restrictive eating plan that should only be followed under the supervision of a registered dietitian nutritionist or other FODMAP-informed healthcare provider.

If you have not been diagnosed with IBS but are experiencing digestive upset, abdominal pain, bloating, distension, and/or irregular bowel movements, talk with a healthcare provider about exploring the possible reasons and conditions contributing to your symptoms. They can guide you in finding the right solution for your health problems.

Benefits of a Low-FODMAP Diet

The main benefits of a low-FODMAP diet is the reduction and management of IBS symptoms. Research has shown that it can improve symptoms in 3 out of 4 people with IBS. This reduction in symptoms can lead to an improved quality of life, improved bowel habits, and overall decrease in abdominal bloating, distension, pain, and discomfort.

After completing phases one and two of the low-FODMAP diet and determining your diet triggers, phase three takes a lot of the guesswork out of eating. This allows you to be more confident about what you eat without being afraid it will cause symptoms.

Common Foods High in FODMAPs to Avoid

FODMAPs are found in many different foods and beverages. While not an exhaustive list, common foods with high-FODMAP content include:

Fruits:

• Apples

• Pears

• Cherries

• Watermelon

• Peaches

• Plums

• Blackberries

Vegetables:

• Garlic

• Onion

• Leek

• Green onion

• Mushrooms

• Cauliflower

• Snow peas

Grains:

• Wheat

• Rye

Legumes:

• Red kidney beans

• Split peas

• Baked beans

• Falafel

Dairy and milk alternatives:

• Cow’s milk

• Yogurt

• Soft cheeses

• Soy milk (made from whole soybeans)

Meat:

• Marinated meats

• Processed meats

Nuts:

• Cashews

• Pistachios

Sweeteners:

• Honey

• High fructose corn syrup

• Sugar alcohols (i.e., sorbitol, xylitol, erythritol)

Foods to Eat on a Low-FODMAP Diet

While there are many foods high in FODMAPs, there are still a good number of foods and beverages that are low in FODMAPs, such as:

Fruits:

• Cantaloupe

• Kiwi

• Orange

• Pineapple

• Blueberries

Vegetables:

• Green beans

• Green bell pepper

• Carrot

• Cucumber

• Lettuce

• Potato

Grains:

• Oats

• Quinoa

• Rice

• Sourdough spelt bread

Protein foods:

• Eggs

• Firm tofu

• Tempeh

• Plain cooked meats/poultry/seafood

Dairy and plant-based milks:

• Hard cheeses

• Lactose-free milk

• Almond milk

• Soy milk (made from soy protein)

Nuts and seeds:

• Macadamia nuts

• Peanuts/peanut butter

• Walnuts

• Pumpkin seeds (pepitas)

Other:

• Dark chocolate

• Maple syrup

• Table sugar

How to Follow a Low-FODMAP Diet

Do not attempt a low-FODMAP diet without the guidance of a healthcare provider. Seek out a FODMAP-trained registered dietitian or gastrointestinal (GI) specialist before starting a low-FODMAP diet. They can help determine if the low-FODMAP diet is right for you, and if so, create a dietary plan to follow.

While the low FODMAP diet is temporary, it can be a big adjustment to your normal eating habits, especially at first.

In addition, a strict no- or low-FODMAP diet is not meant to be permanent, as it can often be low in dietary fiber, which may have an effect on gut health and make GI symptoms worse. If you are at risk of disordered eating, the low-FODMAP diet might not be right for you.

Phase one requires eliminating all major FODMAP triggers from your diet. This phase is recommended to last two to six weeks. This is to allow your symptoms to decrease and see if decreasing FODMAPs will help you manage your IBS.

Phase two is the reintroduction period, when you reintroduce one category of FODMAP foods to your diet one at a time. The length of this phase can vary but generally lasts around eight weeks.

During each category reintroduction, you will start with a small portion of a high-FODMAP food, then increase the portion size over a few days to test your tolerance to each food. Be sure to keep a food diary to record what you ate, how much, and any resulting symptoms.

After you have completed the reintroduction of one FODMAP category, you will go back to a complete high-FODMAP elimination for a  few days to ensure no crossover effects between categories. This process continues until you have tested each FODMAP category.

After you have finished phase two and identified your specific FODMAP triggers, you can begin phase three. Your healthcare provider will help you design a long-term eating plan that allows you the most flexibility and nutrition while also helping you manage your symptoms.

You can follow this eating plan indefinitely, or you may wish to retest or challenge some trigger foods at a later time.

Summary

Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) are a type of sugar that can resist digestion. A wide variety of foods and beverages contain FODMAPs, including some fruits, vegetables, grains and starches, dairy products, legumes, lentils, nuts, and manufactured products.

A low-FODMAP diet is a three-phase eating plan that can help people with irritable bowel syndrome (IBS) identify which foods might trigger them. A low-FODMAP diet is not for everyone. Most people can consume FODMAPs without any symptoms.

A low-FODMAP diet can reduce symptoms and improve quality of life. However, it is important to consult a healthcare professional before beginning one.

Read the original article on Verywell Health.