FODMAP reintroduction: test foods one group at a time
Elimination tells you whether FODMAPs affect you. Reintroduction tells you which ones and how much. Skipping it is the most common mistake people make on the low FODMAP diet, and it leaves them avoiding foods they could eat.
Before you start
- Your symptoms should be clearly better after elimination.
- Keep the rest of your diet low FODMAP during every test, so you only change one thing at a time.
- Ideally, plan the order of tests with a dietitian.
The method
Test one FODMAP group at a time, using a food that contains mainly that group.
| Group | Example test food |
|---|---|
| Fructans | Garlic, onion or wheat bread |
| GOS | Lentils or chickpeas |
| Lactose | Cow’s milk |
| Excess fructose | Honey or mango |
| Sorbitol | Avocado or blackberries |
| Mannitol | Mushrooms or cauliflower |
For each test:
- Day 1: eat a small portion of the test food.
- Day 2: if you feel fine, eat a medium portion.
- Day 3: if you still feel fine, eat a large, typical portion.
- Washout: return to low FODMAP eating for 2 to 3 days, or until any symptoms settle, before the next test.
If you get clear symptoms at any step, stop that test. You have found your threshold for that group. Let symptoms settle before testing the next one.
Record every step
Write down the date, the food, the portion and any symptoms with a severity score. A food and symptom diary makes the results easy to compare when you finish all the groups.
What the results mean
- No symptoms at a typical portion: bring that group back into your diet.
- Symptoms only at large portions: keep enjoying smaller amounts.
- Symptoms at small portions: limit that group for now. Tolerance can change, so it is worth retesting in a few months.
The goal is the most varied diet your gut is comfortable with, not the most restrictive one.