Well done on surviving the low FODMAP phase! If your symptoms have settled then it is now time to regain your food freedom, and tackle the FODMAP re-challenge and reintroduction phase to help you identify your trigger foods.
The goal of this phase is to develop an understanding of your individual tolerance levels to each of the FODMAP groups (1 2). You might discover that you can tolerate a little bit of some FODMAP groups, can eat other FODMAP groups freely, and need to stay on the low FODMAP plan for FODMAPs that trigger symptoms. The good news is that most people find they can successfully reintroduce a couple of FODMAP groups and create a diet with a lot more variety.
Please note that this article does not replace the advice or expertise of a registered dietitian, who specialises in the low FODMAP diet.
Why is Working With a Dietitian Important?
Not everyone is lucky enough to have the help of a FODMAP trained dietitian but if you can, it is a good idea to seek their help. They will be able to work out the type and amount of FODMAPs you can tolerate based on your own personal needs, preference and medical history (1 2 3).
Why Re-Challenge And Reintroduce FODMAPs?
Our gut bacteria love to feast on high FODMAP foods. FODMAPs often act like prebiotics and have a positive effect on our gut health (1 2 3). This means restricting FODMAPs long term could have a negative impact on your overall health.
The low FODMAP diet is also restrictive and socially isolating, as it can be very difficult to eat out or attend potlucks while on the low FODMAP phase. With your new found food freedom you will be able to enjoy a wider range of foods at these events.
Overall long term health and wellbeing can be affected by a strict low FODMAP diet. Reintroducing some high FODMAP foods increases the variety of your diet, and helps it remain nutritionally adequate in the long term.
What To Do When You Find A Trigger Food
The reintroduction phase is a bit like being on a roller coaster, it’s both exciting and terrifying all at the same time. While you might find a few FODMAP friends, at some point you are likely to find a high FODMAP food that triggers your symptoms. Don’t panic! These symptoms will pass within a few days. Focus on the positive (I know this can be hard to do!), which is that you now have a confirmed trigger that you can actively manage. You still may be able to reintroduce this food back into your diet but at a lower level.
How does the reintroduction phase work?
The FODMAP re-challenge and reintroduction phase is a series of food challenges that help you test your tolerance levels to each FODMAP group. One FODMAP group is challenged per week and it is tested for 2 to 3 days during that week (1 2).
If you don’t react to a FODMAP group you can reintroduce these foods once you finish the challenges. If you have a mild reaction then you can reintroduce these foods in small amounts as you feel comfortable. If you strongly react to a FODMAP group then these foods will remain out of your diet to keep your symptoms settled in the long run.
There are two ways you can test FODMAPs. This is the first way:
Test Schedule One
| Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday |
|---|---|---|---|---|---|---|
| Re-Challenge Day | Re-Challenge Day | Re-Challenge Day | Washout Period | Washout Period | Washout Period | If symptom free, start the next test. |
| Small FODMAP Portion (moderate amount of FODMAPs) | Medium FODMAP Portion (high amount of FODMAPs) | Large FODMAP Portion (very high amount of FODMAPs) | ||||
| No symptoms or mild symptoms, continue. Severe symptoms, stop. | No symptoms or mild symptoms, continue. Severe symptoms, stop. | Stop test after completing day three and record symptoms | Start next FODMAP test once symptoms have been settled for three days. |
If you are concerned about testing three days in a row, you can use an alternative testing schedule like test schedule two (4). You can also complete a more gentle reintroduction, where you consume a small FODMAP dose for three consecutive days, and then increase the serving size if it is well tolerated (5).
Test Schedule Two
| Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday |
|---|---|---|---|---|---|---|
| Re-Challenge day: Eat challenge food & monitor symptoms | Rest day: Monitor symptoms | Re-Challenge day: Eat challenge food & monitor symptoms | Rest day: Monitor symptoms | Re-Challenge day: Eat challenge food & monitor symptoms | Rest day: Monitor symptoms | Rest day: Monitor symptoms |
| Small FODMAP Portion (moderate amount of FODMAPs) | Medium FODMAP Portion (high amount of FODMAPs) | Large FODMAP Portion (very high amount of FODMAPs) |
This testing schedule should be used when testing fructans and GOS (5). These FODMAPs move through our digestive system more slowly, and it may take longer for them to trigger a reaction. Also keep in mind that your dietitian might create a testing schedule that is more suitable for your personal needs.
Important Challenge Instructions
Between each re-challenge test you need to be symptom free for at least 3 days, before you start testing the next FODMAP group. If you get moderate to severe symptoms after the first or second test day of eating the challenge food, you should stop the test and consult with your dietitian.
Once you have finished testing a food, do not add it back into your diet until you have finished testing all of the FODMAP groups.
A dietitian can help you tailor the challenges to suit your needs, and they may recommend different re-challenge foods or lower doses.
What are Challenge foods?
Challenge foods are foods that only contain one of the FODMAP groups (1 2 5).
Re-Challenge Schedule & Food Example
| Re-challenge & FODMAP |
Recommended Challenge Foods |
|---|---|
| Re-Challenge 1: Fructose | *1 teaspoon of honey increasing to 2 tablespoons of honey
*1/4 a medium sized mango increasing to 1 medium sized mango |
| Re-Challenge 2: Sorbitol (Polyols) | *3 blackberries increasing to 10 blackberries
*1/4 of an avocado increasing to a whole avocado *1 fresh apricot (use the same serving size for each test day as apricots also contain fructans in larger serves). *Some dietitians may also use coconut or sugar free mints containing sorbitol. |
| Re-Challenge 3: Mannitol (Polyols) | *1/2 Portobello mushroom increasing to 1/2 cup serve
*100g of sweet potato increasing to 200g serve *30g cauliflower increasing to 90g serve |
| Re-Challenge 4: Lactose (Disaccharides) | *125ml milk increasing to 375ml of milk
*1 scoop of ice cream increasing to 3 scoops *200ml of yoghurt (just watch out for added high FODMAP ingredients in the ice cream and yoghurt) |
| Re-Challenge 5 & 6: Fructan Bread, Cereals, Grains (Oligosaccharides). Test two foods from this group. | *1 slice of white wheat bread increasing to 3 slices of wheat bread
*50g wheat pasta increasing to 150g (use the cooked weight of the pasta). |
| Re-Challenge 7 & 8: Fructan Vegetables (Oligosaccharides). Test two foods from this group. | *1/4 of a clove of garlic increasing to 1 clove of garlic
*1/4 of a medium leek increasing to 1/2 whole leek (white and green sections) *1 tablespoon onion increasing to 1/2 onion |
| Re-Challenge 10: Galactans (GOS – Oligosaccharides) | *2 tablespoon serve increasing to 6 tablespoon serve of chickpeas or canned black beans
*Almonds (increase from 15 nuts to 25 nuts) *Boiled red lentils (increase from ½ cup cooked) |
| Re-Challenge 10: Fructose & Sorbitol (only complete if you passed both individual FODMAP tests) | *½ apple or pear increasing to one whole apple or pear. |
(Table References: 4, 5)
For a full list of FODMAP foods you can test with, please see Lee Martin’s Re-challenging and Reintroducing FODMAPS Guide.
Testing fructans at different levels means you are more likely to find a fructan level you can tolerate.
Once you have identified which FODMAP groups are unlikely to trigger your IBS symptoms, you can start slowly adding them back into your diet under the advice of your dietitian, and move onto a long term modified low FODMAP diet.
Happy testing! I hope you enjoy finding your food freedom while maintaining control over your IBS symptoms.
What happens if you react to all the challenge foods?
If you react to all of the re-challenge foods it can mean that the reintroduction phase is not being properly carried out, or that there are additional medical conditions, or food sensitivities that need to be considered. Here are some of the common reasons why you could be reacting:
- Choosing the wrong challenge foods.
Make sure you and your dietitian are choosing challenge foods that only contain one FODMAP (3). For example, a pear would not be a good re-challenge food when testing excess fructose as it contains high levels of both fructose and polyols. If you are trying to test fructose it would be better to choose honey or mango as the re-challenge food as they only contain excess fructose, and will give you a clearer indication of your fructose tolerance levels.
- Not sticking to the low FODMAP diet while undertaking the FODMAP re-challenges
You need to follow a strict low FODMAP diet while completing the re-challenge phase. This means eating low FODMAP foods and using low FODMAP portions sizes while you do your challenges except for your challenge food. Then when you experience symptoms after eating a challenge food, you can be sure the reaction is from that and not something else you have eaten.
It is also advised to avoid eating out and drinking too much alcohol or caffeine, which could skew the results if you react. Alcohol and caffeine are gut irritants even though they are generally low FODMAP (6 7). If you think alcohol or caffeine might be additional IBS triggers, then you can test them at the end of the reintroduction phase with the help of your dietitian.
- Starting the re-challenge test with a high amount of the challenge food.
When testing a challenge food start with a small amount and then increase the amount on the next re-challenge day if you don’t have a severe reaction. For example, if you start by testing one whole clove of garlic your digestive system might freak out. Instead start with ¼ clove per serve and then ½ a clove – you might discover that you can tolerate a small amount and add a little bit back into your diet. Your dietitian can help you decide what testing amounts are appropriate for you.
- Additional intolerances or medical conditions that need to be taken into consideration.
If you find you cannot tolerate any FODMAPs (despite having the guidance of a FODMAP trained dietitian), then further investigation is needed (8 3). It is possible that you could have additional sensitivities to gluten, have food chemical intolerances (histamine, salicylate, amines, glutamates, sulphites), small intestine bacterial overgrowth (SIBO) or another condition that needs treatment (8 3).
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