Phase 2: Reintroduction

23. May 2023
Ida Marie Holm
Ida Marie Holm
Clinical nutritionist

This article explains the reintroduction phase of the diet. Click here to read about phase 1, often called the "strict phase" or the "elimination phase".

Systematic testing of FODMAP groups

When your symptoms have completely subsided, or you only have mild symptoms, you move on to phase two of the diet. Now you should test out certain foods in a systematic way. The aim is to find out which FODMAP groups you react to, and in what quantity. In practice, this means that you test out one food item at a time.

It is important that you are more or less symptom-free when you start this, since the point is to provoke symptoms. Apart from the foods you are testing, you should continue to eat as you have done for the first 2-6 weeks of the diet (i.e. a strict low FODMAP diet).

Test products with only one FODMAP group

We recommend that you start with foods that only contain one FODMAP group. For most FODMAPs, if you tolerate one food containing one type of FODMAP, you usually also tolerate other foods containing the same FODMAP group. The exception to this are the fructans [1]. We therefore recommend dividing the testing of fructans as follows: cereal product, fruit/vegetables, onion and garlic.

Suggestions for foods that are suitable for testing the various FODMAP groups

  • Lactose: milk or natural yoghurt
  • Fructans in grains: wheat bread or light pasta/spaghetti/macaroni
  • Fructans in fruit and vegetables: beetroot (fresh/cooked) or raisins (we recommend testing onions and garlic separately)
  • Fructans in onions: yellow or red onions
  • Fructans in garlic: garlic
  • Fructose: orange juice or sugar snap peas
  • GOS: green peas or almonds
  • Mannitol: cauliflower or sweet potato
  • Sorbitol: avocado or blackberry

Increase the amount a little each day

Once you have selected a food you want to test, start with an amount that is considered moderate FODMAP (for example, ¼ avocado). If you don't get symptoms, the next day you can increase to the amount that is considered high FODMAP (½ avocado). On day three, you can test an even larger amount (for example, the same amount as on day 1 and day 2 combined – ½ + ¼ avocado).

When you get troublesome symptoms, you have found your threshold for the FODMAP group you are testing. Then we recommend that you wait for at least 2-3 days or until the pain subsides before you start again. Maybe you don't get any symptoms at all? Then you can go straight on to the next food item.

Use the Diary to keep track

To keep track of which foods and quantities you test, and any reactions, it is recommended that you keep a log. In the IBS diary in the app, you can easily record both food intake and symptoms, and the diary also helps you see connections between food intake and symptoms.