How To Re-Challenge & Reintroduce FODMAPs

Re-challenge and reintroduction phase of the low FODMAP diet

Testing FODMAPs: How does the reintroduction phase work?

Well done on surviving the elimination phase! If your symptoms have improved significantly then you and your dietitian can now re-challenge the FODMAP groups to see if you can reintroduce certain FODMAPs back into your diet. The goal of this phase is to develop an understanding of your individual tolerance levels to each of the FODMAP groups (Mansueto et al., 2015Mullin et al., 2014). You might discover that you can tolerate a little bit of some FODMAP groups, have no issues with other groups, and need to stay on the low FODMAP plan for certain groups.

Reintroduction Resource

Registered dietitian Lee Martin is a low FODMAP researcher who specialises in the FODMAP reintroduction process. He has written a best practice guide that walks you through the testing and reintroduction process. While my article will give you an overview of the process, this book will give you detailed step-by-step guidelines and a wider range of high FODMAP foods you can use for testing. You can find his resource here.

Please note that this article does not replace the advice or expertise of a registered dietitian, who specialises in the low FODMAP diet. It is strongly recommended that if possible do you do the reintroduction and testing of FODMAPs with the help of a FODMAP trained dietitian.

Why is Working With a Dietitian Important?

It is important that you reintroduce the FODMAP foods under the guidance of a dietitian, as they will help you work out the type and amount of FODMAPs you can tolerate based on your own personal needs and intolerances (Mansueto et al., 2015; Mullin et al., 2014Scarlata, 2014). This reintroduction phase will help you create a varied diet that limits the FODMAPs you have issues with and gives you good IBS symptom control (Mansueto et al., 2015; Mullin et al., 2014Scarlata, 2014). It is very important that you try to reintroduce as many foods as possible because FODMAPs  have a positive prebiotic effect on gut bacteria and gut health (Mansueto et al., 2015; Mullin et al., 2014; Scarlata, 2014). Reintroducing a wide variety of foods is also important to ensure your diet remains nutritionally adequate in the long term.

The reintroduction phase is not easy. It is likely at some stage your IBS symptoms will reappear when you find a trigger food. These symptoms could last for a few days. When this happens it is important to 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?

There are 10 FODMAP re-challenges to complete. One FODMAP group is introduced per week and it is tested for 2 to 3 days during that week (Mansueto et al., 2015; Mullin et al., 2014; Ethical Nutrients, 2012; Laatikainen, 2011). Your dietitian can then advise on whether the FODMAP can be added back into your diet based on your reaction.

There are two ways you can test FODMAPs. This is the first way:

 Test Schedule One

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 settle for three days.

If you are concerned about testing three days in a row you can use an alternative testing schedule (Martin, 2015; Ethical Nutrients, 2012).

 Test Schedule Two

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)    

Your dietitian might create a testing schedule that is more suitable for your personal needs.

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.

It is important to note that your dietitian might recommend introducing the re-challenge foods at a lower dose to see if you can tolerate the FODMAP at a lower level. This means that you need to talk to your dietitian before starting the re-challenging & reintroduction phase, so they can tailor it to your personal needs (Laatikainen, 2011; Mullin et al., 2014).

Additionally, you need to be symptom free for at least 3 days before you start testing a re-challenge food. If you get severe symptoms after the first or second test day of eating the re-challenge FODMAP food you should consult with your dietitian. After three days of being without symptoms you can start testing the next FODMAP group under the guidance of your dietitian.

What are re-challenge foods?

Re-Challenge foods are foods that only contain one of the FODMAP groups (Gibson & Shepherd, 2012; Mansueto et al., 2015; Mullin et al., 2014).

Here is an example of a testing schedule and recommended re-challenge foods.  If possible you need the guidance and expertise of a FODMAP specialised dietitian as many factors can influence the testing process.

Re-Challenge Schedule

Re-challenge & FODMAP
Recommended Re-Challenge Foods
Re-Challenge 1: Fructose 1 teaspoon of honey increasing to 2 tablespoons of honey or 1/4 a medium sized mango increasing to 1 medium sized mango (Gibson & Shepherd, 2012; Mansueto et al., 2015; Martin, 2015).
Re-Challenge 2: Sorbitol (Polyols) 3 blackberries increasing to 10 blackberries. Some dietitians may use 1/4 of an avocado increasing to a whole avocado as the challenge food (Martin, 2015).
Re-Challenge 3: Mannitol (Polyols) 100g of sweet potato increasing to 200g serve. Or 30g cauliflower increasing to 90g serve (Martin, 2015). Some dietitians may use celery to test mannitol tolerance.
Re-Challenge 4: Lactose (Disaccharides) 60g (1/4 cup) yoghurt increasing to 250g (1 cup) or 125ml milk increasing to 375ml of milk (Martin, 2015; Gibson & Shepherd, 2012; Mansueto et al., 2015).
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; or 50g cooked buckwheat kernels increasing to 150g; 30g rice krispies increasing to 60g serve (Martin, 2015).
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; or 1/4 of a medium leek increasing to 1 whole leek (white and green sections); or ¼ onion increasing to 1 whole onion (Martin, 2015; Gibson & Shepherd, 2012; Mansueto et al., 2015).
Re-Challenge 9: Fructan Fruit (Oligosaccharides) Test one food. 100g grapefruit increasing to 300g serve or 1 dried date increasing to 4 dried dates (Martin, 2015).
Re-Challenge 10: Galactans (GOS – Oligosaccharides) 2 tablespoon serve increasing to 6 tablespoon serve of thawed peas or canned black beans. Some dietitians will test galactans using almonds (increase from 15 nuts to 25 nuts) (Martin, 2015).


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 three different levels means you are more likely to find a fructan level you can tolerate. This means that you might be able to add some fructan containing foods back into your diet depending on your tolerance levels.

Your dietitian may give you a different list of foods to test or different amounts of re-challenge foods to test. It is highly important that you follow their guidance.

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.

What happens if you react to all the re-challenge foods?

Sometimes when you react to all of the re-challenge foods it can mean that the reintroduction phase is not being properly carried out, or there are additional medical conditions or sensitivities that need to be considered. Here are some of the common reasons why you could be reacting to all re-challenge foods:

  • Choosing the wrong re-challenge foods.

Make sure you and your dietitian are choosing re-challenge foods that only contain one FODMAP (Scarlata, 2014). For example, a pear would not be a good re-challenge food as it contains high levels of both fructose and polyols, which means it has multiple FODMAPs (Monash University App, 2014). If you are trying to test fructose it would be better to chose honey or mango as the re-challenge food as they only contain excess fructose, and will give you a clearer indication of whether you can tolerate fructose or not (Scarlata, 2014).

  • Not sticking to the low FODMAP diet while undertaking the FODMAP re-challenges

Stick to a strict low FODMAP diet while completing the re-challenge phase (Gibson et al., 2013; Scarlata, 2014). Make sure you stay within the safe serving sizes for low FODMAP foods to help reduce your overall FODMAP load (Monash University App, 2014). This means 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 have a reaction to them. Alcohol and caffeine are gut irritants even though they are generally low FODMAP (BPACnz, 2014; Monash University App, 2014). If you think alcohol or caffeine might be additional IBS triggers, then you can test them at the end of your reintroduction phase with the help of your dietitian.

  • Starting the re-challenge test with a high amount of the re-challenge food.

When testing a re-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 (Ethical Nutrients, 2012; Scarlata, 2014). 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 will tell you 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 dietitian who has FODMAP specialisation), then further investigation is needed (Gibson et al., 2014; Scarlata, 2014; Scarlata, 2014). 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 (Gibson et al., 2014; Scarlata, 2014).

Happy testing! I hope you can look forward to being able to expand your diet while maintaining control over your IBS symptoms.


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