What is a low-FODMAP diet?

What are FODMAPs?

FODMAPs are carbohydrates or sugars found in food that your body may find difficult to digest. This is because these sugars are poorly absorbed and pass through the small intestine to the colon, where they are fermented by gut bacteria. This fermentation produces excess gas that may stretch the bowel causing bloating, wind and pain. Water may also move into and out of the colon resulting in diarrhoea, constipation or a combination of both. People who have been given a diagnosis of IBS appear to be more susceptible to these problems.

The FODMAP acronym stands for the different types of sugars in this category:

Fermentable – these are foods which we do not fully digest so they end up being fermented by bacteria in the colon

Oligosaccharides – these are two main groups – fructans and galacto-oligosaccharides – which are found in garlic, onion, legumes and wheat

Disaccharides – includes sucrose, lactose in dairy foods and maltose in grains

Monosaccharides – these are simple sugars, such as fructose and glucose and are found in fruit, honey and sugar drinks

And Polyols – these are found in stone fruit, sugar-free sweeteners like xylitol and sorbitol, as well as some vegetables including mushrooms.

Read more about popular diets such as the sirtfood diet and IBS diet. Plus, check out some of our delicious low FODMAP recipes, from baked sea bass to herb omelette with fried tomatoes.

What is the low-FODMAP diet?

The low FODMAP diet was developed by scientists at Monash University in Australia and has been adapted for the UK by researchers at Kings College, London. The diet is for people with IBS and other specific digestive issues who may find eliminating certain foods helps to alleviate some or all of their symptoms. The objectives of the diet are to identify the IBS triggers relevant to you and develop a management strategy for going forward.

How to follow a low-FODMAP diet

The diet should only be conducted under the supervision of a dietitian or other appropriate healthcare professionals. Foods considered to be high in FODMAPs (such as those listed below) are eliminated from the diet for a period of time (approximately 2 to 6 weeks) and replaced with suitable low-FODMAP alternatives. After about 2-6 weeks of the initial elimination stage, you should see some improvements in your symptoms and at this point you can progress to the challenge phase. Under the guidance of your dietitian, you methodically introduce amounts of one type of FODMAP food in a controlled and gradual manner. This helps ascertain what level of tolerance you might have to certain foods. The information will help to enable reintroduction without the food triggering your symptoms.

During this challenge phase you will re-introduce each FODMAP GROUP separately over a period of about 3 days; you should expect this phase to take approximately 8-12 weeks. Once you have established the foods that make your symptoms worse, you can build a personal diet plan for long-term symptom control together with your dietitian.

High FODMAP foods that should be minimised:

This is not a definitive list and further details should be sought from your dietitian. You can also check on foods and safe quantities here.

Fructans (chains of fructose) containing foods:

• Wheat (including bread and breakfast cereals)
• Rye
• Barley
• Garlic
• Leek
• Onion
• Artichoke
• Lentils
• Chickpeas
• Legumes
• Cashews
• Pistachios
• And as an ingredient (e.g. inulin, FOS, oligifructose) added to some packaged foods

Galacto-oligosaccharides containing foods:

• Baked beans
• Lentils
• Borlotti beans
• Chickpeas
• Soybeans
• Kidney beans

Lactose containing foods:

• Milks from mammals
• Custard
• Ice cream
• Condensed milk
• Evaporated milk
• Yogurt
• Dairy desserts

High fructose containing foods:

• Apples
• Pears
• Mangoes
• Watermelon
• High-fructose corn syrup
• Honey

Polyol containing foods:

• Nectarines
• Peaches
• Plums
• Cauliflower
• Mushrooms
• Sugar snaps
• Chewing gum
• Confectionery with polyols
• Some 'sugar free' products

Low FODMAP foods that are OK to eat:

FODMAPs occur in carbohydrate foods; this means protein foods and fats and oils, that do not contain carbs, may be FODMAP free.

Fruit, vegetables and some grains may be considered low-FODMAP but it is worth bearing in mind that the amount of the food you eat may make a difference - so although a particular vegetable may be considered low in FODMAPs, when eaten in quantity, its effects may be more like that of a moderate or high FODMAP food.

Protein foods:

• Meat, including poultry, served without a sauce or coating
• Fish and shellfish as well as tinned fish in brine or oil
• Eggs
• Tofu and tempeh

Fats, oils and spreads:

• Butter, ghee, lard and suet
• Cooking oils and margarine

Cereals, grains and starchy foods:

• Rice
• Oats
• Quinoa
• Buckwheat
• Tapioca
• Potatoes
• Corn and polenta

Fruits (these are examples of low FODMAP fruits – note some portion sizes may need to be restricted):

• Blueberries
• Cantaloupe and honeydew melon
• Lemon and lime
• Kiwi (restricted to 2)
• Pineapple
• Tomatoes (fresh)

Vegetables (these are examples – note some portion sizes may need to be restricted):

• Aubergine
• Carrot
• Courgette
• Parsnip
• White potato
• Radish
• Rhubarb

This is not a definitive list – please refer to your dietitian or healthcare provider for more information.

What are the benefits of the FODMAP diet?

Those with IBS symptoms appear to be sensitive to the gases and the fluid changes that occur in the colon when the diet contains lots of FODMAP foods. Minimising FODMAPs has been shown to improve gut symptoms in most people with IBS-like symptoms.

Can the low-FODMAP diet be used for weight loss?

The low-FODMAP plan is NOT a weight-loss plan, it is a prescriptive plan adopted for a specific, short-term purpose only.

Is the FODMAP diet safe to follow in the long term?

The low FODMAP diet is NOT designed to be a 'diet for life' as many high FODMAP foods that the diet restricts are important for maintaining long term health. One of the reasons for this is that these foods help promote the diversity and growth of the beneficial bacteria that reside in your gut.

It's important to remember not everyone will have a problem with every FODMAP. Some people might have symptoms triggered by one or two types of FODMAPs, whereas others may be sensitive to all five. The reasons for this are unknown, but foods should only be restricted if they contribute to your symptoms.

The diet is intended to be individualised according to the FODMAPs that cause you a problem, so it is very important to seek guidance from a registered dietitian and to follow the diet for the minimum amount of time needed to determine the foods (and the amounts of those foods) that trigger your symptoms.

What is the evidence for the low-FODMAP diet?

When IBS is a confirmed diagnosis, the low-FODMAP diet can be very effective. It is supported by science and, if followed correctly, has proven to reduce symptoms. In fact, research shows that up to 86% of people who follow a low-FODMAP diet notice a significant improvement in their symptoms.

Is the low-FODMAP diet healthy? A nutritionist's view...

A low-FODMAP diet is very restrictive, especially at the start when you eliminate all foods that are high in FODMAPs. For this reason, before you start the elimination phase you should attempt to identify other possible triggers such as caffeine, spicy foods, alcohol and irregular eating patterns.

This is also not a diet to do on your own - a dietitian can help you re-introduce high FODMAP foods at the right time and guide your interpretation of their effects on your symptoms. They will also ensure that while you conduct the diet, you continue to eat foods that will provide all the nutrients you need to stay healthy and well. Following the low-FODMAP diet can be a challenge, but the efforts are well worth the rewards.

It is important to remember that FODMAP foods are generally good for you - they are only restricted by the plan for a limited time and only to determine what aggravates your symptoms. Once this is understood, you and your dietitian will be able to determine which foods, and at what quantity, are safe to include in your diet.

Who shouldn't follow the low-FODMAP diet?

Even though some FODMAP foods are poorly absorbed by us all, they only need to be restricted if they cause you symptoms. This means a FODMAP is not something that most of us need to be concerned about and the majority of us do not need to follow this diet. Its design and application is specifically for those who have received a medical diagnosis of IBS or other relevant digestive condition.

A word of advice, if you suspect you suffer from IBS, speak with your GP. It is important to exclude coeliac disease and other possible medical conditions first. If IBS is confirmed as the cause of symptoms, then a low-FODMAP diet under the guidance of a dietitian may be beneficial.

Enjoyed this? Now read...

Does diet affect gut health?
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Digestive health recipes and tips

Get inspired with our low FODMAP recipes...

Basic omelette
Anytime eggs
Salmon & lemon mini fishcakes
Baked sea bass with lemon caper dressing
Raspberry sorbet

For more tempting ideas, visit our low FODMAP diet recipe collection.

This page was reviewed on 29th September 2023 by Kerry Torrens, Registered Nutritionist.

Emer Delaney BSc (Hons), RD has an honours degree in Human Nutrition and Dietetics from the University of Ulster. She has worked as a dietitian in some of London's top teaching hospitals and is currently based in Chelsea.

This article was reviewed on 8 August 2018 by nutritionist Kerry Torrens.

Kerry Torrens is a qualified Nutritionist (MBANT) with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food.

All health content on goodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.
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