After 4-8 weeks on the FODMAP elimination diet, it’s important to reintroduce problem foods. This is because by eliminating all the groups you could be missing out on nutrients, not to mention enjoyment!

Introducing is easy but there are a few rules:

  1. Only begin reintroducing when you have followed the low FODMAP diet for 4-8 weeks and are showing no symptoms.
  2. Reintroduce one food at a time (I explain how below), and allow three symptomless days before reintroducing further.
  3. Even if you reintroduce a food successfully without symptoms, in order to continue reintroducing other FODMAP foods, you must revert back to a fully low FODMAP diet until all your reintroductions are complete.

how to reintroduce

I really recommend seeing a dietician familiar with the low FODMAP diet to guide you through this process. The official booklets that I was provided with, produced by Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, really helped me and marked quite a turning point in my journey to alleviate symptoms. I am able to mark in my progress and write notes that I can refer back to later, which is super helpful.

Now, all the FODMAP groups apart from fructans are really easy to introduce. Apart from fructans, if you tolerate one food with a certain FODMAP, you will probably be fine with the entire group.
e.g. if you are fine with honey, you will be fine with all fructose containing foods.

This means that reintroducing isn’t as lengthy a process as you might have thought. The difficulty comes with fructans, which need to be tested individually, of course with the 3 symptomless days in between challenges.

It’s also recommended that you mix up your introductions a bit, i.e. don’t test fructan after fructan, but rather sandwich fructan challenges with other FODMAP groups.

So, how to do it? I’ll use onion (fructan) as an example here. This is the pattern you should follow:

Day 1: 1 tbsp of raw / cooked onion in a low FODMAP meal.
Day 2: no symptoms? Continue with 2 tbsp of raw / cooked onion.
Day 3: no symptoms? Continue with 3 tbsp of raw / cooked onion.

Now, if you get any symptoms during the challenge, stop the challenge as this is an indication you are intolerant to that food / group.

If you don’t get symptoms, you must wait three days to ensure this remains the case. If it does, you are officially tolerant of that food / group. Hooray! You must hold off reintroducing it into your diet permanently however until you have completed all your challenges.


but what about foods that contain more than one fodmap?

There are many foods that contain multiple FODMAPs, such as coconut water, mushrooms, rye, cashews and many sweet fruits. These need to be reintroduced individually, just like you would a fructan containing food.


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