Irritable bowel syndrome (IBS) is a condition that causes digestive symptoms, such as abdominal pain, diarrhea, or constipation. A person may find that what they eat has an effect on how IBS manifests.

However, symptoms of this condition are highly individual. People can react differently to different foods, and their other symptom triggers can vary as well.

As a result, there is no single IBS diet that will work reliably for everyone. Often, people have to try different options to find what suits them best.

In this article, we look at some of the IBS diets that could help, what they involve, and how to choose one. We also look at other factors that can cause IBS to flare up, and suggest when to contact a healthcare professional.

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There is no single diet that can help all people with IBS. This is because a person with IBS may have specific foods that trigger their IBS symptoms.

The International Foundation for Gastrointestinal Disorders (IFFGD) recommends a person keep a diary for 2–3 weeks to try to identify trigger foods or food groups.

People can use the diary to track:

  • the food and liquids they consume each day
  • the symptoms they experience, including their timing and severity
  • other factors that may play a role, such as stress and hormonal fluctuations

People can also bring this diary to medical appointments with a doctor or dietitian.

If the diary does not help a person understand their IBS triggers, they may benefit from trying an elimination diet.

An elimination diet is one where a person removes specific foods or food groups from their diet for a period of time to see whether this improves their symptoms.

The IFFGD recommends trying elimination diets over a period of 12 weeks by following these steps:

  1. Make a list of foods that may contribute to IBS symptoms. If unsure which foods cause symptoms, track them using the food diary technique or remove common triggers first, such as fiber or caffeine.
  2. Choose one food or food group on the list and remove it from the diet for 12 weeks.
  3. If there is no improvement in IBS symptoms, reintroduce that food and eliminate a different one.

The IFFGD suggests removing fiber from the diet first, as it can be an IBS trigger, even in those who experience IBS with constipation.

It is important to get supervision from a doctor or dietitian while trying this approach. Eliminating foods from the diet can make it difficult to get the required amount of nutrients. A medical professional can help ensure this does not happen.

FODMAP stands for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.” These are types of short-chain carbohydrates that are present in certain foods. Some people with IBS find that foods high in FODMAPs can trigger their symptoms.

Researchers from Monash University in Melbourne, Australia, developed the Low FODMAP Diet to help with this. The diet involves eating low FODMAP foods in the right portion sizes for a set period of time.

Research from 2016 reports that up to 86% of people with IBS found that a low FODMAP diet reduced their symptoms.

The following table provides some examples of foods that contain either high or low levels of FODMAPs. However, it is not a complete list of foods or portion sizes that are low FODMAP. People can find the full list on the Monash University website. Monash University has also developed a mobile app.

Food groupHigh FODMAPLow FODMAP
vegetablesgarlic, onions, and other alliums
beans, including black eyed beans and baked beans
soy beans
dried fruits
kiwi fruit
citrus fruit
dairy and alternativescow’s milk
cream cheeses
soy milk made from whole soybeans
almond milk
mature, hard cheeses
soy milk made from soy protein
proteinsome marinated or processed meats if they contain high FODMAP seasoningplain meats
breads and cerealsanything containing wheat or rye flour, including breads, cookies, crackers, baked goods, pasta, and couscoussourdough bread
spelt bread
basmati rice
sugary foodshigh fructose corn syrup
artificially sweeteners such as sorbitol, mannitol, and xylitol
dark chocolate
maple syrup
table sugar
nuts and seedscashews
macadamia nuts
pumpkin seeds

To try the diet, follow these steps:

  1. For 2⁠–6 weeks, avoid high FODMAP foods, replacing them with low FODMAP foods instead. This can involve significant dietary changes, so it may be helpful to have the assistance of a dietitian.
  2. After 6 weeks, begin gradually reintroducing one type of FODMAP at a time by eating one specific food that contains it. For example, a person can test out their tolerance for fructose by eating honey.
  3. Eat a small, controlled portion of that food, gradually increasing it over the course of 3 days. During this time, monitor for symptoms.
  4. If a person develops symptoms or develops them after they reach a certain portion size, they can write this down in order to remember what they tolerate and what they do not.
  5. Repeat these steps for all of the types of FODMAP over the next 8–12 weeks.

After this period, people can balance low FODMAP foods with higher FODMAP foods that they may be able to tolerate.

For some people, increasing fiber intake can relieve IBS symptoms, such as chronic constipation.

There are two main categories of fiber: soluble and insoluble. Soluble fiber dissolves in water and is present in foods such as fruits, oats, and beans. Insoluble fiber does not dissolve in water and is present in whole grain foods.

Doctors often recommend soluble fiber to people with IBS. However, both forms of fiber can help with different IBS symptoms in some people.

Foods that are high in insoluble fiber can help add bulk to a person’s stool, making bowel movements easier to pass. However, insoluble fiber may also cause diarrhea, bloating, or pain.

Soluble fiber can help reduce bloating and excess gas production. However, some sources of soluble fiber are also high FODMAP.

Generally, it is best to try this approach by gradually increasing fiber intake. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) recommends a person add 2⁠–3 grams of fiber to their diet per day until they reach a level that works for them.

If increasing fiber intake makes symptoms worse, a person can try increasing the intake more slowly. If that does not help, they may wish to try a different approach.

There are other factors, aside from the foods a person eats, that can contribute to IBS symptoms. These include:

  • stress
  • anxiety
  • too much or too little exercise
  • eating too much or too quickly
  • hormonal fluctuations, such as those that occur before menstruation
  • certain medications

A person may wish to use a symptom diary to track these factors too. It may be that a combination of dietary and lifestyle changes can help. For example, people can try:

Mindful eating

Chewing food slowly and thoroughly helps with digestion. It can also prevent a person from swallowing air, which may contribute to feeling bloated. It is advisable to avoid carbonated drinks, particularly at mealtimes.

Moderate exercise

A person should also get regular exercise, if possible. This can benefit both mental and physical health and may reduce constipation.

Addressing mental health

While IBS is a physical disorder, people with the condition are more likely to have experienced traumatic events in early life, according to the NIDDK.

A 2018 meta-analysis found that early trauma and post-traumatic stress disorder increased the likelihood of IBS across over 648,000 participants. Trauma can have a long-term impact on mental and physical health.

Some people may find it helpful to discuss this with a trauma-informed therapist. Reducing stress overall is also generally beneficial for digestion, even if it is not a direct IBS trigger.

Learn more about the effects of stress on the body here.

A person should contact a doctor or dietitian before making any major dietary changes. A person should also consult with a doctor if they notice any signs of malnutrition, such as:

A dietitian can help a person try out different IBS diets, create meal plans, and advise on vitamin or mineral supplements, if necessary.

Learn more about what dietitians and nutritionists do here.

There are numerous IBS diets that people can try in order to manage their symptoms and gain better quality of life.

However, it is important to remember that what works for one person may not work for another. Sometimes, a combination of dietary and lifestyle changes is necessary.