You’ve completed the elimination phase of the low FODMAP diet and you’re feeling fantastic. Then, your Dietitian asks you to begin your FODMAP challenges. Surely it would just be easier to stay on the low FODMAP diet forever, right? Not so fast! Following a low FODMAP diet is a diagnostic tool, not a forever diet. In fact, many FODMAPs act like prebiotics and have a positive effect on our gut health. It is important to remember that the ‘elimination’ phase is designed to set you up to complete the just-as-important ‘reintroduction’ phase. Today, on the blog, we will explain the FODMAP reintroduction phase, and the potential issues and anxieties associated with this time. We will then answer commonly asked questions about FODMAP reintroduction.
What is the FODMAP reintroduction phase?
The reintroduction phase aims to identify which FODMAP groups are well tolerated, and which ones are problematic. This reduces the need for an over-restrictive elimination-style diet, which can limit foods high in prebiotics and plant variety. The reintroduction phase is structured and systematic, like running an experiment.
Each week during the reintroduction phase, you’ll choose one of the FODMAP groups to challenge (oligosaccharides, disaccharides, monosaccharides, or polyols). You’ll eat a food from that group over a three-day period, each day increasing the amount of the food you re-introduce. Most importantly, during the challenge, you’ll monitor your gut symptoms and evaluate how well you tolerate the specific FODMAP group. This series of self-experiments will help you determine which FODMAP groups you can eat abundantly, the ones you may need to enjoy in small serves and which FODMAPs you might want to limit altogether to keep your gut calm.
Potential issues associated with FODMAP reintroduction and their solutions:
Introducing more than one FODMAP group at a time
Just like you learned in middle school science class, you only want to change one variable in your experiment at a time. In the reintroduction phase, we want to have one FODMAP that we’re testing with any given challenge food. For example, apples contain fructose and sorbitol so are not an appropriate challenge food, because we can’t easily determine whether it is the fructose or the sorbitol causing the symptoms. Whereas honey contains fructose so is a good challenge food to choose when re-introducing fructose.
Rushing through the re-introduction phase
There is no rush to completing the reintroduction phase of the low FODMAP diet. Rushing through the challenge only undermines your progress and may leave you feeling confused about which foods cause your symptoms. Take your time and make sure you wait until any symptoms have settled and then have a two to three-day rest period between each challenge. This will make sure you are not overloading your gut and feel ready to complete each reintroduction.
Potential anxiety associated with FODMAP reintroduction and their solutions:
Experiencing uncomfortable symptoms
It is understandable to be concerned about experiencing uncomfortable IBS-related symptoms, particularly if you have felt symptom relief over the initial low FODMAP phase, the elimination period. To address this anxiety, keeping a record of your challenges is very helpful in describing the effects of each of your challenges. Make sure you record the portion of the food you ate, the types of symptoms (if any) and severity. Think of keeping a symptom diary as writing up the results of your experiment!
‘Failing’ all reintroductions
You may be concerned that you will ‘fail’ all reintroductions and react to every single challenge food, even in small quantities. While this anxiety is warranted, it is often a result of re-introduction not being completed properly. Here are some troubleshooting tips you can put in place to optimise your chances of determining your FODMAP thresholds:
- Start small. Always start with a small amount of the FODMAP-containing first, as the smallest amount of the food may be your threshold. If you don’t experience a strong reaction, then you may like to increase the quantity of the food the following day.
- Not remaining on a low FODMAP diet. Think back to science class – your controlled variables are important! In other words, you want to control the environment in which reintroduction takes place. After you’ve tested a food, do not add it back into your diet until you’ve finished challenging the remaining groups.
If you are feeling particularly anxious about the reintroduction phase, you may want to consider halving the FODMAP challenge food amounts and doubling the time it takes to do the re-introductions. This is a gentler approach to reintroduction and may reduce the severity of symptoms returning if you are sensitive to the group that you are challenging.
Your common reintroduction questions answered:
Q: I’ve been low FODMAP for years, have had issues any time I try to re-introduce. Is this normal?
A: If you have been low FODMAP for years, it is likely that your body, namely your gut microbes, are very used to this diet. You may like to take a gentler approach to FODMAP reintroduction. As mentioned above, you may want to consider halving the FODMAP challenge food amounts and doubling the time it takes to do the re-introductions.
Q: What order should I reintroduce foods in? What are the most common FODMAPs people find they can successfully re-introduce?
There is no strict order to reintroducing foods, but it should be structured and systematic. You’ll likely do around 8 to 10 challenges in total. We typically recommend starting with the FODMAPs that tend to be well tolerated and then moving on to the more challenging ones. Here is a suggested list in order of the typically best tolerated to worst tolerated FODMAPs to reintroduce, with examples of foods and their portion sizes:
Excess fructose – ¼ of a mango increasing to 1 mango
Sorbitol – ¼ avocado increasing to ¾ of an avocado
Mannitol – ¼ portobello mushroom increasing to 1 portobello mushroom
Lactose – 60mL cow’s milk increasing to 250mL cow’s milk
Fructan containing grain – 50g wheat pasta (cooked) increasing to 200g
Fructan (garlic) – 1/4 of a clove of garlic increasing to 1 clove of garlic
Fructan (onion) – 1 tablespoon onion increasing to 1/2 onion
GOS – 1/4 cup canned chickpeas (rinsed) increasing to 1 cup
Fructan + sorbitol (only to be completed if excess fructose and sorbitol challenges were passed) – ¼ apple increasing to one whole apple
Q: How do I get over anxiety of the re-introduction phase?
It is comfortable to stay in the safety of the elimination phase, but the reintroduction phase is what allows you to follow the low FODMAP diet sustainably. Remember that the ‘elimination’ phase is designed to set you up to complete the equally important ‘reintroduction’ phase. When you find out what your triggers are, you will have a lot more food freedom. It will be easier to eat out, easier to enjoy food with friends and family, and far less restricting. Many FODMAP-rich foods are not unhealthy, in fact, many help the growth of good gut bacteria. Refer to the section above about common anxieties when reintroducing FODMAPs to your diet also.
Q: Do I have to be on a low FODMAP diet again if I want to reintroduce other FODMAPs in future?
It is advisable to reintroduce FODMAP containing foods that you reacted to again at least once per year. Our bodies and gut microbiota profiles are constantly changing, so it is possible that you can tolerate foods that you perhaps didn’t once tolerate. While reintroducing foods, you should stick to the formula of changing one thing at a time and keeping the environment the same with each reintroduction. As such, it is advisable to stick to a low FODMAP diet if reintroducing foods in the future.
For more options of low FODMAP foods download the FODMAP Friendly App, available for Apple /iPhones and Android.
In summary
Think of the reintroduction phase of the low FODMAP diet as ‘short term pain for long term gain’. The key to reintroduction is to take it slowly but surely, introducing one FODMAP-containing food at a time while remaining on a low FODMAP diet. Anxiety around reintroduction and the anticipated uncomfortable symptoms is normal, but you can work to pinpoint which foods cause your symptoms by keeping a diary. If you need more support, a FODMAP-trained Dietitian will be of immense help through the re-introduction phase. They will be able to answer your questions and give you personalised advice through this process.
Written by: Charlotte Barber (Student Nutritionist)
Reviewed by: Kiarra Martindale (Accredited Practising Dietitian)
