Having now completed the low FODMAP diet for the full 8 weeks (time does really fly!) the next phase was to reintroduce the foods high in FODMAPs back into our diet.  Following the low FODMAP diet had become part of our daily eating routine, and after 4 weeks it quickly became fairly easy to follow with not much thought needed regarding appropriate choices required.  However, the diet is not designed to be forever, rather it is designed to reduce the overall load of FODMAPS in the diet to reduce  severity of symptoms – and then to re-introduce to your personal tolerance levels. This became tricky for us, given that we do not have diagnosed IBS and were not looking for a significant reduction of symptoms along  with the necessary identification of problem FODMAP foods when reintroduced. We did however complete a couple of trial reintroductions, to become familiar with the process and share some tips about how this can practically be done.  As you need to keep the low FODMAP diet rolling along in the background whilst re-introducing the right amount of test food at the right time we found it can be difficult to incorporate into meal planning, especially as you are meant to test a particular food three days in a row.

One option is to just cook the same low FODMAP meal three days in a row and increase the dose of the test food (if your not getting any symptoms of course).  We decided to do it the harder, but more interesting way and incorporate the test foods into meals & snacks and an example of how we tested a high FODMAP food is shown below;

Test Food: Mushrooms
Test Sugar: Polyols
Test Amount Day One: 40g (roughly 4-5 mushrooms depending on size)
Test Meal Day One: We had a meal at a chain restaurant and the chicken dish I ordered came with, what I’m going to guess, is about 40 grams of mushrooms or maybe just slightly less. Which worked out perfectly for my test on Day One!

Test Amount Day Two: 80g
Test Meal day Two: Gluten free pasta with homemade pesto & mushrooms

Test Amount Day Three: 120g (usually half a pack of supermarket bought mushrooms)
Test Meal Day Three: Garlic (infused oil) & parsley mushrooms on gluten free toast

I chose mushrooms because 1. I love them, 2. I missed them & 3. They fit into loads of meals I would usually cook 🙂 like this Polenta & Mushroom dish I cooked yesterday and could also have been used as a suitable low FODMAP meal with a test food.


Some tests are definitely easier than others however; for example when you test fructans (such as wheat, onion, broccoli) which are found in many foods you will be glad there are some foods containing fructans that can be had as a snack rather than needing to incorporate them into a full meal. Bringing fructans back into the diet by trying 2 slices of bread was easy and enjoyable, and provided the first opportunity to enjoy some delicious fresh bread! There are many different foods which contain fructans, and so you should always test a few different ones (or more if you want), especially if you feel fructans are a particular problem for you.


There are no rules to what foods you choose when it comes to the re-introduction phase, but it is likely more support may be required. At this point we would recommend for anyone following the diet to speak to your healthcare professional for more assistance and some pointers of where best to start.  Make sure you do complete the re-introduction phase fully so that you can incorporate as much variety of low FODMAP and high FODMAP containing foods into your diet. A wide variety is key to your digestive health and you may even find benefits once they are reintroduced. It is understandable why some people are reluctant to complete this phase fully especially if their symptoms have been significantly reduced by the diet and the thought of getting those symptoms back are quite scary.

It is worth noting that the symptoms experienced from the re-introducing of foods may in some cases seem worse than before the low FODMAP diet was started, and this may be due to not having these foods in your diet on a regular basis.  Foods high in FODMAPs are also prebiotics, meaning they provide food for the good bacteria in your gut, which is a good thing and is an important part of a balanced healthy diet.  By not consuming foods containing these prebiotics you may affect the natural flora in your gut which could lead to more gastrointestinal and other problems in the future.  This is a very interesting topic which is being researched as part of the whole FODMAP evidence base and something we will blog about to pass on the scientific information not everyone has access to.

The main aim is to ensure you keep yourself and your gut healthy for the long-term, but more to come on this soon….



Lee is a UK Registered Dietitian who worked as a researcher at King’s College London University researching the low FODMAP diet for irritable bowel syndrome (IBS). Previously Lee worked for the NHS with many years’ experience of treating IBS. Lee has run a popular blog on the low FODMAP diet since 2013 where you can learn all about his experiences of following the low FODMAP diet, find information on the research behind the diet, the practicalities of implementing the diet along with low FODMAP meal and baking recipes. This year Lee has published the first ever book dedicated to the reintroduction phase of the low FODMAP diet. More information on the book entitled ‘Re-challenging and Reintroducing FODMAPS: A self-help guide to the entire reintroduction phase of the low FODMAP diet’ can be found on the website

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