Low FODMAP not for life

April 8, 2017

With the interest and success of the low FODMAP diet, the diet is being taken up by thousands of people internationally. This is great news. Finally a strategy to improve symptoms for the majority with IBS.

As with anything there is a downside… The rapid uptake of the diet, which for many does not include guidance from an experienced dietitian, has led to a vast number of people following a strict low FODMAP diet long term.

Why are some people so strict with the low FODMAP diet?

  1. Fear of symptoms returning if you eat high FODMAP foods
  2. Confusion over the misinformation on the internet regarding which foods are safe
  3. Belief that it is a diet for life and, in most cases
  4. All of the above

How long should you be on the low FODMAP diet for?

The truth is the low FODMAP diet is designed to be followed strictly for an initial 2-6 weeks until symptoms resolve. At that stage, gentle reintroductions are encouraged by your dietitian to learn your level of tolerance. This will depend on how severe your symptoms are, what type of symptoms you experienced (e.g. constipation or bloating or diarrhoea may have different trigger FODMAPs), and what your normal dietary habits are. This phase is becoming less of a “challenge” phase, where you would typically eat large portions of high FODMAP foods to test for a reaction, rather testing small amounts of moderate and high FODMAP foods to include them safely in your diet without a significant symptomatic response.

Why is reintroduction of FODMAP foods so important?

Relaxation of FODMAP restrictions is important for several reasons. Firstly, it ensures patients include a varied diet, incorporating a wide range of foods rich in nutrients for optimal health. Secondly, research has demonstrated that FODMAPs are prebiotics. This means they are a food source for bacteria, encouraging the growth of good bacteria with potential health benefits. Recent studies have shown that by adhering to a strict low FODMAP diet, levels of some of our good bacteria fall [1, 2]. We reduce FODMAPs to improve IBS symptoms because they are fermented and produce gas, but we need them in the diet long term to obtain the right balance of gut bacteria.

So please include some FODMAPs in your diet. We understand not everyone will be able to eat onion today, tomorrow (or ever). Please seek the advice of one of our experienced dietitians to help guide you through the process to give you the best chance of a healthy gut microbiome.


  1. Staudacher, H.M., et al., Fermentable Carbohydrate Restriction Reduces Luminal Bifidobacteria and Gastrointestinal Symptoms in Patients with Irritable Bowel Syndrome. The Journal of Nutrition, 2012. 142(8): p. 1510-1518.
  2. Halmos, E.P., et al., Diets that differ in their FODMAP content alter the colonic luminal microenvironment. Gut, 2015. 64(1): p. 93-100.

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