What is a low FODMAP diet?

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are the chemical names of 5 naturally occurring sugars that are not well absorbed by your small intestine.

In some people with irritable bowel syndrome (IBS), these sugars can trigger symptoms, such as:

• diarrhoea
• flatulence (farting)
• abdominal pain and bloating
• constipation

These symptoms can affect your life, make you feel uncomfortable and cause embarrassment.

A low FODMAP diet has 2 stages.

1. In the first stage you temporarily reduce foods which contain these sugars. This helps you to identify if your symptoms are triggered by one of these sugars.
2. In the next stage you learn how much of these foods you can eat before your symptoms appear. This way of eating is often followed permanently. This can help people with IBS control their symptoms.

How was the low FODMAP diet developed?

The low FODMAP diet was developed by researchers at Monash University in Victoria, Australia.

The researchers identified which foods are low in FODMAPs and high in FODMAPs. This helps people with IBS identify how much of these foods they can eat.

Which foods are high in FODMAPs?

Many foods contain FODMAPs. Some of these foods are:

• garlic
• onions
• apples
• green peas
• some marinated meats
• dairy products (e.g., milk and yoghurt)
• chickpeas
• wheat, barley and rye-based bread

People with symptoms of IBS may find it helpful to limit the amounts of high FODMAP foods they eat. And increase the amount of low FODMAP foods they eat.

Low FODMAP foods include:

• red capsicum
• oranges
• grapes
• eggs
• plain cooked meat
• oats
• rice
• dark chocolate
• peanuts

For a complete list of high and low FODMAP foods, visit the Monash University FODMAP website.

They also have an app which helps you identify low FODMAP foods — Monash FODMAP app.

What if I want to start a low FODMAP diet?

If you are considering a low FODMAP diet, you should consult a dietitian. They can:

• advise you on which foods to eat and which foods to avoid
• help you reintroduce certain foods back into your diet so you can figure out which foods trigger your IBS

How to follow a low FODMAP diet

A low FODMAP diet is not a lifetime diet. It’s usually recommended for 2 to 6 weeks at a time. This will let your IBS symptoms get better. You should see a dietitian before following a low FODMAP diet.

If your symptoms have improved, you can start to reintroduce one FODMAP food at a time. This is called a ‘FODMAP challenge’. Each challenge lasts around 3 days, during which you can record any IBS symptoms you have. FODMAP challenges will help figure out which foods trigger your IBS symptoms.

Based on this information, you can then follow a diet that:

• includes FODMAP foods you can tolerate
• restricts the foods that trigger your IBS symptoms

Some people find that they only need to avoid some high FODMAP foods, not all of them.

If your symptoms have not improved on the FODMAP diet you should see a dietitian for advice on other therapies.

Possible side effects of low FODMAP diets

There are a wide range of foods you may need to modify if you have IBS. So while you’re on the first stage of a FODMAP diet, your levels of certain nutrients may drop. These include:

• calcium
• iron
• dietary fibre
• vitamins
• protein

Because of this, it’s important that you see a dietitian. They can suggest low FODMAP alternatives to ensure you still get adequate nutrients. You may also need to take vitamin and mineral supplements in the short term.

Will a low FODMAP diet work for me?

Before you begin a low FODMAP diet, you should work with your doctor. They can help make sure that what you have is IBS and not another condition such as:

• inflammatory bowel disease
• coeliac disease
• bowel cancer

Sometimes, IBS symptoms can be triggered by things other than FODMAPs in the diet, such as:

• high fat foods
• alcohol
• caffeine
• stress

Your dietitian can help you identify if these other things are an issue for you.

If you follow the low FODMAP diet and your symptoms don’t improve, speak to your dietitian. They can suggest other therapies, including stress reduction and fibre supplements.

Resources and support

For more information about a low FODMAP diet:

• visit the Monash University FODMAP website
• contact an accredited practising dietitian
• visit your doctor

If you have IBS, you can seek support from the Irritable Bowel Information and Support Association of Australia.