What is a Low FODMAP diet?

A diet low in FODMAPs is an effective treatment for gut symptoms such as bloating, wind, abdominal pain and an altered bowel habit, usually associated with IBS.

FODMAP stands for 'fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. The low FODMAP diet does not take on the question of what causes IBS, rather it looks at the role that certain foods play in triggering digestive symptoms. 

The main dietary sources of the four groups of FODMAPs include: 
 - Oligosaccharides: Wheat, rye, legumes and various fruits and vegetables, such as garlic and onions.
 - Disaccharides: Milk, yogurt and soft cheese. Lactose is the main carb.
 - Monosaccharides: Various fruit including figs and mangoes, and sweeteners such as honey and agave nectar. Fructose is the main  carb. 
 - Polyols: Certain fruits and vegetables including blackberries and lychee, as well as some low-calorie sweeteners like those in sugar-free gum. 

The low FODMAP diet was developed by a team at Monash University in Melbourne, Australia. It has been successfully adapted to the UK by researchers at King’s College London and implemented at Guy’s and St Thomas’ NHS Trust in London FODMAP foods are foods that contain certain types of carbohydrates.

Why might FODMAPs affect my gut symptoms?:  

Once ingested, some FODMAPs do not get absorbed in the small intestine. They increase the amount of water in the small intestine which may contribute to loose stools.

They also pass along the gut to the large intestine where there are billions of bacteria which ferment them. This fermentation may result in gas production and symptoms such as wind and bloating. Reducing the intake of FODMAPs has been shown to improve gut symptoms in most people with functional bowel disorders like irritable bowel syndrome (IBS). 

Benefits of a Low-FODMAP Diet: IBS digestive symptoms can vary widely, including stomach pain, bloating, reflux, flatulence and bowel urgency. Stomach pain is a hallmark of the condition, and bloating has been found to affect more than 80% of people with IBS. 

Needless to say, these symptoms can be debilitating. Fortunately, both stomach pain and bloating have been shown to significantly decrease with a low-FODMAP diet. Evidence from four high-quality studies concluded that if you follow a low-FODMAP diet, your odds of improving stomach pain and bloating are 81% and 75% greater, respectively.

Who Should Follow a Low-FODMAP Diet?: 

A low-FODMAP diet is not for everyone. Unless you have been diagnosed with IBS, research suggests the diet could do more harm than good. This is because most FODMAPs are prebiotics, meaning they support the growth of good gut bacteria. Also, most of the research has been in adults. Therefore, there is limited support for the diet in children with IBS. 

If you have IBS, consider this diet if you: 
 - Have ongoing gut symptoms.
 - Haven't responded to stress management strategies. 
 - Haven't responded to first-line dietary advice, including restricting alcohol, caffeine, spicy food and other common trigger foods 

It is important to be aware that the diet is an involved process. For this reason, it's recommended that you work with a trained dietitian who can guide you through the appropriate foods.

How do I follow the low FODMAP diet? 

There are 3 stages to the low FODMAP diet: 

Stage 1 Restriction: In this stage, you reduce your FODMAP intake by avoiding foods that are high in FODMAPs for 4 to 8 weeks as this period is considered long enough to identify if symptoms will respond to a low FODMAP diet. 

Stage 2 Reintroduction: If your symptoms have improved following FODMAP restriction, it is important to reintroduce some high FODMAP foods. This will enable you to identify which FODMAPs you are most sensitive to, as well as how much of a high FODMAP food triggers your symptoms.

Stage 3 Personalisation : The long term aim of a low FODMAP diet  is to personalise your diet so you  only avoid foods that trigger your symptoms and you return to as normal a diet as possible. 

I want to try the low FODMAP diet. What should I do?

The low FODMAP diet is quite a complex approach and so it is important that you receive good quality advice about how to follow the different stages. A registered dietitian, preferably one with experience of educating people on the low FODMAP diet, will help you to follow it carefully. He/she will ensure you follow a healthy balanced diet by providing you with ideas for suitable low FODMAP alternatives.