If you’ve successfully completed the first phase of your low FODMAP diet and are not sure where to go from here, then this article was made for you! Hopefully, you’ve felt improvement in your IBS symptoms and that low FODMAP foods help your gut feel calmer. Now is the time to safely reintroduce FODMAP-containing foods to gain a greater sense of food freedom and diversity back into your diet. Today on the blog, we’ll give a recap of the initial low FODMAP phase and discuss how the second phase works, including which foods to re-introduce, amounts and orders of reintroduction. We’ll round off with our top three tips on reintroduction.
The initial low FODMAP phase – a recap
The initial phase is the trial phase of the low FODMAP diet that removes all medium and high FODMAP groups, even if you think they are well tolerated. The purpose of this phase is to determine whether removing FODMAPs makes a significant difference to symptoms. This step usually lasts around two to six weeks. We often get asked about the timing of this phase – as following a low FODMAP diet for two weeks is quite different to six! The timing of the initial phase is largely dependent on how long it takes for you to experience symptom relief on the low FODMAP diet. Some people with IBS may find it only takes two weeks on the low FODMAP diet for them to feel less bloated, constipated or gassy, while for others, their digestive system takes longer to adapt and experience relief. Unfortunately, sometimes symptoms can worse before they get better and having a broad two to six-week initial phase suggestion accounts for this. Although it may seem illogical, the best time to re-introduce FODMAPs is once you’ve started to feel better following a low FODMAP diet. This ensures that your diet is minimally restrictive while providing relief from IBS symptoms.
How does the reintroduction phase of the low FODMAP diet work?
You’ve completed the initial 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 initial low FODMAP phase is designed to set you up to complete the just-as-important ‘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 – similar to 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.
Which foods to re-introduce
When choosing which foods you’ll reintroduce in this phase, keep in mind that the aim is to test the FODMAP, not the food. Like any good scientific study, we want to have one independent variable, or FODMAP we’re testing. This means that there should be one dominant FODMAP in the challenge food. For example, apples contain fructose and sorbitol so are not an appropriate challenge food. This is because we can’t easily determine whether it is the fructose or the sorbitol causing the symptoms. You want to pick a food where there is one main FODMAP, like honey which contains fructose. Honey is thus a good challenge food to choose when re-introducing fructose. We have included example foods below.
Reintroduction food portion guide
When it comes to portions with reintroduction foods, you want to start with a moderate dose on day one and increase as tolerated to a high and then very high dose on days two and three. If possible, aim to eat your challenge dose in one go, rather than spreading it across the day. Your largest dose can be separated over two meals but should be consumed within one to three hours.
For example, if you’re testing the oligosaccharides in wheat through wheat pasta, you might start your first portion as half a cup. The next challenge might be one cup, and the very high dose would be one and a half cups.
Order of reintroducing foods
There is no strict order to reintroducing foods, but it should be structured and systematic. You’ll likely do around eight to ten 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 order with examples of foods and their portion sizes:
Excess fructose – ¼ of a mango increasing to 1 mango
Sorbitol – ½ small apricot increasing to 2 small apricots
Mannitol – ¼ portobello mushroom increasing to 1 portobello mushroom
Lactose – 60mL cow’s milk increasing to 250mL
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 – 1/2 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 1 whole apple
The FODMAP Friendly top three tips on reintroduction
- 1. Take your time
There is no rush to completing the reintroduction phase of the low FODMAP diet. Rushing through the challenges 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 three-day rest period between each challenge. This will make sure you are not overloading your gut and feel ready to complete each reintroduction. - 2. Keep a symptom diary
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 thought you are writing up the results of your experiment! - 3. Seek professional support as you need
A FODMAP trained Dietitian is a great person to have on your IBS management team. A Dietitian can perform a full patient assessment, including a symptom assessment and diet. They will be able to answer all of your FODMAP questions, and help you choose the best course of action in completing the reintroduction phase. They can map out this process and arm you with the educational support you need to succeed.
To summarise
The low FODMAP initial phase will take around 2-6 weeks to complete, while the reintroduction phase will take around 6-8 weeks. It is important to take these timings as a guide rather than prescription and not rush the process. Keeping a diary of your symptoms is a great step to determining which FODMAP containing foods are your personal triggers. Finally, a FODMAP trained Dietitian will be of immense help through the reintroduction phase. They will be able to answer your questions and give you personalised advice through this process. Remember that the initial low FODMAP phase is designed to set you up to complete the equally important ‘reintroduction’ phase.
Written by: Charlotte Barber (Student Nutritionist)
Reviewed by: Kiarra Martindale (Accredited Practising Dietitian)
