Food is one common trigger for digestive conditions such as irritable bowel syndrome (IBS).
Avoiding high FODMAP foods is the cornerstone of some of the most common IBS diets.
But is it really worth cutting out those fermentable carbohydrates and following a low-FODMAP diet?
Let’s do some digging and find out!
FODMAPs are a collection of carbohydrates that contribute to IBS symptoms like gas, bloating and stomach pains.
To spell this out:1
Some (but not all) carbohydrates are poorly absorbed in the small intestine. As a result, they move further through the gut and ferment in the large intestine.
In people with IBS, this can trigger symptoms such as bloating, constipation, wind, diarrhoea, stomach pain and flatulence.
The guiding theory of a low FODMAP IBS diet is to replace high FODMAP foods that are poorly digested with low FODMAP foods that easily break down in the stomach.
This decreases the fermentation of sugars in the large intestine. Consequently, this can reduce bloating, constipation and other IBS symptoms.
However, IBS sufferers aren’t all sensitive to the same high FODMAP foods. To help reduce IBS symptoms, a dietitian may recommend you eliminate high FODMAP foods for a short period.
They are then gradually reintroduced in phases to identify which exact foods you are most sensitive to. It can also show which are better tolerated.
A low-FODMAP diet is not quite as simple as cutting out all high-FODMAP foods and focusing on low-FODMAP foods. It usually involves the following three stages:
This stage usually lasts a few weeks and requires strict avoidance of high-FODMAP foods.
Once you find adequate relief of IBS symptoms then you can move onto the next stage.
This next step requires reintroducing high-FODMAP foods to see which type and amount of high-FODMAP foods are affecting you the most.
It is recommended that you reintroduce foods one at a time – and it is recommended that you use a dietician to help guide you through this process.
This stage allows you to know which FODMAP foods you need to restrict, and which ones are actually fine to consume.
For example, you may be fine eating a piece of wheat bread every day but may want to avoid cauliflower all the time.
As you can see, a low FODMAP diet is a significant dietary intervention. And unless you have diagnosed IBS and have exhausted all other IBS diet options, it can do more harm than good.
The lists of high- and low-FODMAP foods below show how complex and restricted a low FODMAP diet can be.
Just to reiterate, a low FODMAP diet isn’t for everyone. But that’s not to say you can’t take inspiration from some of the theory.
For example, keeping a food diary to track the severity of your symptoms against what you’ve consumed.
Most of us can’t remember exactly what we eat on a day-to-day basis. This is why it can be helpful to write it down.
This visibility allows you to recognise patterns between your diet and IBS symptoms. With this knowledge you could then reduce or eliminate a food for a short period to see if it has an impact on symptoms.
This is a simple but effective way to, see how an individual food may be causing your digestions problems.
It’s always recommended that any changes to diet are done in consultation with your GP or a dietitian.
FODMAPs can be found in varying amounts in a wide variety of foods.
Some foods contain just the one, e.g. only fermentable carbs, whereas others can contain several different types.
In many cases, high FODMAP foods are to blame for IBS symptoms. So, it makes sense to cut them out, right?
But whilst there’s growing evidence to show restricting these foods can drastically improve IBS symptoms, it takes serious commitment.
Here is a comprehensive list of high FODMAP foods which you should avoid/reduce if you want to follow this diet (especially in the first reduction stage).2
It’s not all doom and gloom though, there are also lots of foods that are perfectly fine to eat while following a low-FODMAP diet.
Here are some of the most common ‘safe’ foods and the quantities you should limit certain foods to.
Following a low FODMAP IBS diet is not a decision to take lightly. Only attempt it if:
This final point is particularly important.
If this is a diet change you would like to initiate, careful implementation is crucial.
A FODMAP trained dietitian can assess if it’s appropriate for your IBS symptoms and also ensure what you’re eating continues to be nutritionally sufficient.
Eliminating high FODMAP foods isn’t a long-term solution.
This is where IBS diets can differ from allergy diets.
It’s important to recognise, IBS is not caused by a food allergy. It has nothing to do with your immune system.
Whereas diets for food allergies and intolerances often involve permanent exclusion of an allergen, this is not usually required in IBS diets.
For example, after the initial elimination period in a FODMAP diet, most IBS sufferers can start to tolerate small to moderate quantities of high FODMAP foods.
Remember, diet is only one cause of IBS. If lifestyle factors, such as stress, are the trigger of your IBS symptoms, making behavioural changes could be more valuable.
In addition, if you suffer with food anxiety of any form, or have other underlying health conditions, it’s particularly important to seek medical guidance before pursuing an IBS diet.
Last updated: 10 August 2021
Joined Holland & Barrett: Jan 2018
Bsc in Nutrition, Registered Associate Nutritionist and Certification in Pre and Post Natal Nutrition
Donia started her career as a freelance nutritionist, later she joined Nestle as their Market Nutritionist to help support their healthier product range, before joining the team at Holland & Barrett in January 2018.
Donia has over 6 years experience as a Nutritionist and also works with clients on a one to one basis to support their goals which include weight loss, prenatal and postnatal nutrition and children’s health.