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

Systematic Testing of FODMAP Groups

Once your symptoms have subsided completely or are only mild, it's time to start reintroducing foods. In this phase, you systematically test specific foods to determine which FODMAP groups you react to and in what quantities. This is done by testing one food at a time.

It is important to mostly symptom-free before you begin, as the goal is to provoke symptoms. Apart from the foods you are testing, you should continue to follow the strict low FODMAP diet that you have had for the first 2-6 weeks.

Start with Foods Containing Only One FODMAP group

We recommend starting with foods that contain only one FODMAP group. Generally, if you tolerate one food containing a specific FODMAP, you are likely to tolerate other foods containing the same FODMAP.

The exception is fructans, where we recommend testing them in different categories: grains, fruits and vegetables, onion, and garlic [1].

Suggested Foods For Testing Different FODMAP groups

• Lactose: Milk or plain yoghurt
• Fructans in grains: White bread or wheat pasta/spaghetti/macaroni
• Fructans in fruit and vegetables: Beetroot (fresh/cooked) or raisins (Onions and garlic should be tested separately)
• Fructans in onions: White or red onion
• Fructans in garlic: Garlic
• Fructose: Orange juice or sugar snap peas
• GOS: Green peas or almonds
• Mannitol: Cauliflower or sweet potato
• Sorbitol: Yellow peach or blackberries
• Perseitol*: Avocado

Gradually Increase the Amount

Once you have chosen a food to test, start with an amount that is considered moderate FODMAP, such as 1 slice of white bread. If you experience no symptoms, increase the amount the next day to an amount that is considered high FODMAP, such as 1.5 slices. On day three, test an even larger amount, such as two slices.

If you develop bothersome symptoms, you have found your tolerance level for that particular FODMAP group. In that case, we recommend waiting at least 2-3 days, or until your symptoms subside, before continuing testing. If you experience no symptoms, move directly on to the next food. Remember to maintain a low FODMAP diet aside from the foods you are testing.

Expand Your Testing

Once you have established your tolerance levels for different FODMAP groups, you can start testing larger quantities, more frequent consumption, and combinations of different FODMAP groups. For example, if you tolerate both white bread and lactose well, test them together to see if your tolerance changes.

To ensure your diet is as well-suited to your needs as possible, we recommend testing foods you eat frequently in the portion sizes and frequency you prefer. Some foods may be better tolerated if consumed every other day rather than daily.

Keep Track with the Diary

To keep track of which foods and quantities you are testing, along with any symptoms, we recommend keeping a log. The IBS diary in the app allows you to easily record food intake and symptoms, helping you identify correlations.

*Perseitol is a rare sugar alcohol naturally found in avocados. Since it differs from other sugar alcohols, we recommend testing avocado separately if it is a part of your diet. Learn more about avocados and FODMAPs here: New FODMAP-assessment of avocado 🥑

[1]. Monash University. Fructans and FODMAP Reintroduction (2020). Available at: https://www.monashfodmap.com/blog/fructans-fodmap-reintroduction/

[2]. Monash University. Avocado and FODMAPs - A Smashing New Discovery! (2024). Available at: https://www.monashfodmap.com/blog/avocado-and-fodmaps-a-smashing-new-discovery/