The low fodmap diet

The low FODMAP diet is an internationally recognised evidence-based diet that is often recommended to people with irritable bowel syndrome (IBS). FODMAPs stands for "Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols".

Fodmaps are groups of short-chain carbohydrates and sugar alcohols that are poorly absorbed by the small intestine and can cause digestive symptoms in some people. The low FODMAP diet involves avoiding foods that are high in FODMAPs for a period of time (usually 2-8 weeks), and then gradually reintroducing them to determine which specific FODMAPs trigger your symptoms. Frequently I meet with people who have been advised to follow a low fodmap diet for a couple of weeks by their GP and a low fodmap diet is not the first dietary approach. Similarly I see many people who have been following a low fodmap diet for a long time and simply just removed all high fodmaps from their diet. There are 3 stages to a low fodmap diet which will be explained shortly; and all are important in helping you identify your personal triggers.
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Few points to consider before starting a low fodmap diet

  • A low fodmap diet is complicated and if not done correctly might not give you the clarity you need but could give you a restricted and nutritionally unbalanced diet.
  • This diet is not intended to be a long-term solution, but rather a short-term elimination diet to identify trigger foods.
  • Whilst low fodmap is not low fibre anecdotally I find some people who are prone to constipation can become more constipated whilst on the diet, this can however be prevented if supported through the diet with a fodmap trained specialist

How do fodmap foods cause gut problems?


Fodmaps travel through the digestive tract and reach the large bowel where they are broken down by your gut bacteria and it is this fermentation process that can produce gas and other by products, which cause symptoms such as bloating, abdominal pain, and diarrhoea in people with sensitive digestive systems.


Additionally, FODMAPs are very small carbohydrates and they can pull water into the small intestine and this extra gas and water in the large intestines can alter the motility of the large intestine, contributing to either diarrhoea or constipation. This video helps explain this further:


The 3 stage process

Stage One – elimination

The first stage involves a 2-6 week elimination of high FODMAP foods and the goal is to achieve adequate symptom improvement. This stage only tells you that one or more fodmap trigger your symptoms


Stage Two – rechallenge

This stage is where you challenge your tolerance to individual fodmap foods through a structured reintroduction process to identify which fodmaps might be your trigger and how much can you tolerate of individual fodmaps. For example you would challenge yourself with milk or yogurt, increasing the portion over 3 days to determine your tolerance to lactose.


Stage Three – personalisation

This stage is where you mix different fodmaps and finding out your unique fodmap threshold.

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What foods can you eat or avoid on a low fodmap diet?

There are many foods you can continue to enjoy on a low fodmap diet including:

  • Carbohydrates: potatoes, rice, oats, cornflakes,
  • Fats: butter, oil, dark chocolate
  • Protein: eggs, meat, fish, hard cheese
  • Fruit and vegetables: carrots, green beans, spinach, peppers, grapes, satsumas, strawberries, kiwis, herbs

Fodmap rich foods include wheat and wheat products such as bread and pasta, onion, garlic, pulses including chickpeas, cashew nuts, certain fruits (such as apples, pears, and mangoes) and dairy products. Whilst this might sound very restrictive with the correct support you can enjoy a wide variety of foods

Next Steps

If you feel the low fodmap diet is the next step remember it is important to make sure you have a correct diagnosis of IBS and other potential causes such as coeliac disease, inflammatory bowel disease or some cancers have been ruled out. Check out this blog on how to get IBS diagnosed: Do I have Irritable Bowel Syndrome? How can I get it diagnosed?


I can support you through a low fodmap diet and work with you to develop a personalized, well-balanced eating plan. Click here to get in touch: Contact


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