Low FODMAP Diet: What it is & Benefits for IBS

The low FODMAP diet is an internationally recognised dietary approach for symptom management of certain digestive conditions.

When people say “FODMAP diet,” they usually mean a diet low in FODMAP — certain sugars that may lead to intestinal inflammation. This diet is designed to help people with irritable bowel syndrome (IBS) and/or small intestinal bacterial overgrowth.

In this article we will be discussing the low-FODMAP diet, what it is, and how it can help with IBS and other digestive disorders.

What is the Low FODMAP Diet?

FODMAPs are found in a wide variety of foods, including fruits, vegetables, legumes, grains, milk products, and sweeteners.

‘FODMAP’ stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols, which are a form of short-chain carbohydrates (sugars) that are poorly absorbed by the small intestine in some individuals. They are typically found in high-carbohydrate foods.

A list of high FODMAP foods to avoid includes:

  • Dairy-based milk, yoghurt and ice cream

  • Wheat-based products such as cereal, bread and crackers

  • Beans and lentils

  • Some vegetables, such as artichokes, asparagus, onions and garlic

  • Some fruits, such as apples, cherries, pears and peaches, ripe bananas

  • Low carbohydrate foods such as meat, fish, and eggs tend to be lower in FODMAPs.

A list of low-FODMAP substitutes includes:

  • Grains: sourdough spelt bread, quinoa flakes, corn flakes, oats, plain rice cakes, and sourdough bread and pasta made from quinoa, rice, or corn

  • Vegetables: eggplant, green beans, bok choy, red bell pepper, carrot, cucumber, lettuce, potato, and courgette

  • Fruit: melon, kiwi fruit, pineapple, mandarin, pineapple, orange, and unripe bananas

  • Dairy and alternatives: almond milk, rice milk, lactose-free milk, soy milk (made from soy protein), brie, camembert, feta cheese, and hard cheeses

  • Sugars and sweeteners: maple syrup, table sugar, rice malt syrup, and dark chocolate

  • Proteins: beef, chicken, eggs, fish, lamb, pork, prawns, tempeh, and tofu

  • Nuts and seeds: walnuts, macadamias, peanuts, pumpkin seeds, sunflower seeds

Whilst teas and coffees are low-FODMAP foods, caffeinated beverages are also usually discouraged on a low-FODMAP diet because caffeine can be a trigger for those with IBS.

The low FODMAP diet typically follows a 3-step elimination protocol where high FODMAP foods are avoided for some time and then reintroduced as symptoms improve. These foods are typically re-introduced slowly after 4-6 weeks.

How Does the Low FODMAP Diet Work?

FODMAPs can be difficult to digest for some people. This can lead to bloating, wind and diarrhoea due to poorly digested food particles in the colon.

FODMAPs draw fluid into the bowel and can quickly begin to ferment, producing gas. The increased gas can distend the bowel leading to bloating, pain and discomfort.

Gut bacteria that feed on FODMAPs also tend to produce hydrogen. Excess hydrogen in the gut can then cause abdominal cramping, pain, discomfort, and constipation.

In some people, these foods can cause bowel contents to move faster or slower. This can lead to either diarrhoea or constipation.

The low FODMAP diet aims to eliminate these hard-to-digest foods to reduce digestive distress and inflammation in the gut and reduce the risk of bacterial overgrowth.

Not everyone will have this reaction to FODMAPs, and this diet is not intended to be a cure for IBS but can be an effective symptom management strategy. For some, it can help put their IBS into remission and identify trigger foods.

Benefits of the Low FODMAP Diet for IBS

So, what are the benefits of the low FODMAP diet?

The low FODMAP diet has been shown to improve IBS symptoms in up to 86% of people.

By removing irritants, the gut lining is given a chance to repair itself and can restore a healthy balance of gut flora. This can reduce symptoms of bloating, constipation, food intolerance, and general digestive distress while improving the quality of life for IBS patients.

However, not everyone with IBS will see improvement on the low FODMAP diet, and any dietary changes should always be done under the guidance of a GP or dietary professional.

Low FODMAP Diet: Potential Drawbacks

The Low FODMAP diet has several challenges.

Firstly, it may alter the gut microbiota and reduce our bacterial diversity due to its reduction in fibre, which supports a healthy gut flora - especially the lactobacilli strains. This reduces the bacterial diversity within our gut which can weaken our immune system.

Secondly, it is a restrictive approach to eating and can impact our nutrient intake and diet quality, which can be particularly difficult when eating out.

Lastly, up to 30% of patients don’t respond to the diet and remain symptomatic.

IBS patients who follow the low FODMAP diet tend to eat less of the fibre and prebiotics that supports beneficial microbes in the gut. In the short term, a diet like this may lessen symptoms of IBS, but may not be sustainable as a long-term approach to eating.

For these reasons, it is advised to not follow a low FODMAP diet unless it is believed necessary in your treatment plan. Before trying the FODMAP diet, it is advised to improve the overall quality of your diet and identify other potential triggers, such as caffeine, spicy foods, and irregular meal times.

It’s always advised to talk to your GP or work with a qualified dietician before starting a new dietary protocol to get the most out of your treatment.


In conclusion, the low FODMAP diet can be very effective for those with IBS or for anyone wanting to reset their gut health. The low FODMAP diet is part of the therapeutic dietary approach for those with IBS and SIBO.

Combining dietary and lifestyle changes, medications, and stress management techniques is often the best approach for treating IBS.

We advise you to work with your GP or a qualified dietician to find the best SIBO and IBS treatments that work for you and your gut.

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