Studies have shown low FODMAP diets can help improve symptoms of irritable bowel syndrome.

FODMAP stands for 'fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.' FODMAP foods are types of carbohydrates, including sugars that easily inflame the digestive system and those that are poorly absorbed in the gut.

Irritable bowel syndrome (IBS) is a widespread gastrointestinal disorder affecting 11 percent of the world's population, this according to a report from Clinical Epidemiology.

Fast facts on FODMAP foods and IBS:

  • Diet is the best way to manage IBS symptoms.
  • Low and high FODMAP foods include many types vegetables, meats, fish, cereals, grains, and eggs.
  • Knowing the difference makes it easier to go on a low FODMAP diet, and alleviate IBS symptoms.

Woman at desk experiencing stomach pains.Share on Pinterest
IBS symptoms may include recurring, continuous pain or discomfort in the abdomen, bloating, nausea, and indigestion.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, about 10 to 15 percent of adults in the United States are affected by IBS.

Of that number, less than 7 percent will receive a diagnosis of IBS, either because a doctor is unsure or because the individual is not seeking help for symptoms. It seems that women are affected by IBS in higher numbers than men.

IBS causes the following symptoms:

  • abdominal discomfort in the pain or abdomen
  • bloating and gas
  • feeling bowel movements are incomplete
  • inability to empty bowels
  • white mucus in stool
  • constipation
  • diarrhea
  • indigestion
  • nausea

The exact cause of IBS is unknown. People with IBS can find symptom relief with diet changes, medication, stress management, behavioral therapy and various alternative therapies.

Low FODMAP diets have shown promise for managing IBS.

What is a low FODMAP diet?

Blueberries, raspberries, strawberries.Share on Pinterest
Blueberries, raspberries, and strawberries may be eaten freely on the FODMAP diet. Blackberries, however, should be avoided.

The FODMAP diet was developed by a team of researchers from Monash University, Melbourne, Australia. The team, led by Peter Gibson, was the first to prove low FODMAP diets improved IBS symptoms.

FODMAP foods are classified as high, medium and low. The diet details that those with IBS should avoid high FODMAP foods, eat some medium FODMAP foods, and depend on low FODMAP foods as staples.

Low FODMAP foods (things to eat freely) include:

  • Vegetables: Lettuces, chives, cucumber, fennel, eggplant, broccoli, and baby spinach.
  • Fruits: Blueberries, raspberries, strawberries, pineapple, grapes, and kiwifruit.
  • Meats: Chicken, beef, turkey, cold cuts, and lamb.
  • Fish: Crab, lobster, salmon, tuna, and shrimp.
  • Fats: Oils, seeds, butter, peanuts, and walnuts.
  • Starches, cereals, and grains: Potatoes, gluten-free bread, quinoa, brown rice, tortilla chips, and popcorn.

High FODMAP foods (things to avoid) include:

  • Vegetables: Garlic, asparagus, onions, mushrooms, black beans, shallots, and scallions.
  • Fruits: Blackberries, watermelon, prunes, peaches, dates, and avocados.
  • Meats: Sausages, breaded meats, battered meats, meats served with garlic or onion based sauces and fillings.
  • Fish: Breaded fish, battered fish, fish served with garlic or onion based sauces.
  • Fats: Almonds, cashews, pistachios, avocado.
  • Starches, cereals, and grains: Beans, lentils, wheat and gluten-based bread, rye, muffins, pastries, and pasta.

Knowing the difference between high, medium and low FODMAP foods makes it simple to incorporate them into a diet.

It is important to talk to a doctor or dietitian before starting a low FODMAP diet. They are not typically recommended for long-term use because they eliminate some essential nutrient-rich foods and can significantly reduce healthful gut bacteria. Many FODMAPs are prebiotics, which means they support good gut bacteria.

Anyone with IBS who is experiencing the following might consider a low FODMAP diet:

  • continued gut symptoms despite lifestyle and diet changes
  • no response to stress management practices
  • no symptom relief even after removing trigger foods, such as coffee, alcohol, and spicy foods.

Nutritionist discussing food plan with patient.Share on Pinterest
It is a good idea to discuss the FODMAP diet with a nutritionist or doctor, to ensure it is appropriate.

While the data on gluten-free diets and IBS fall short, there is evidence supporting low FODMAP diets for managing IBS symptoms.

One 2014 clinical trial, comparing effects of low FODMAP diets in people with and without IBS, found IBS symptoms were improved by up to 50 percent with a low FODMAP within a week of implementing the diet.

People saw improvements with abdominal pain, bloating, stool consistency and flatulence.

One 2016 report in Clinical and Experimental Gastroenterology, found that up to 86 percent of people with IBS saw improvements in their symptoms while on a low FODMAP diet.

One current 2017 report out of the King's College London, London, United Kingdom, found that low FODMAP foods are beneficial for people with IBS and that other diets, including gluten-free, do not even come close to offering similar positive benefits.

In another 2017 review, this one from the University of L'Aquila, Italy, researchers similarly concluded low FODMAP diets offer favorable results for IBS symptoms but did not go so far as to conclude that FODMAP diets are superior to conventional diets.

It is important to note low FODMAP diets are restrictive and should be temporary. This is because low FODMAP diets cut out many nutrient-rich foods.

A low FODMAP diet involves three phases:

  1. Elimination: In this phase, which can last from 3 to 8 weeks depending on their response, a person eliminates all high FODMAPs from their diet.
  2. Reintroduction: Once the elimination phase is over, individuals can start reintroducing FODMAP types into their diet one at a time, about every 3 to 7 days, to see which foods trigger their symptoms.
  3. Maintenance: The maintenance phase involves going back to eating as normal as possible, limiting the FODMAP foods that cause IBS symptoms and maintaining this practice. Eventually, some people may be able to incorporate all or most FODMAPs back into their diet with no symptoms.

Studies show symptom improvement can continue after the reduction of FODMAPs in the diet and for a long time afterward, provided that people avoid the FODMAPs that trigger their symptoms.

Useful resources for low FODMAP diets and specific foods to include and remove in a low FODMAP diet are the International Foundation for Functional Gastrointestinal Disorders and the Monash University app.

For low FODMAP recipe inspiration, see dietitian Kate Scarlata's blog, For A Digestive Peace of Mind.

A low FODMAP diet may help improve symptoms of IBS, but not everyone responds well to this diet. Therefore, anyone interested in going on a low FODMAP diet should talk to their doctor or a dietitian regarding the benefits and risks.