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The risks of following a low FODMAPs diet. 6 things you need to know before you start a low FODMAPs diet. Gut specialist dietitian Amanda Moon

Are you following a low FODMAPs diet? If you are, read on as this information is key to your longterm health.

The low FODMAPs diet is an investigative elimination diet I use with many of my clients, and is being recognised as the one of the most effective dietary interventions for managing the symptoms of IBS.  Three out of four people with IBS will experience improvement in symptoms when they follow a low FODMAPs diet.

However, there are a few risks of following a low FODMAPs diet so I have shared a few things I’d like you to understand before getting started or if you have been doing the diet for a while already.

FYI. The risks of following a low FODMAPs diet. 5 things you need to know before you start a low FODMAPs diet

The risks of following a low FODMAPs diet

  1. Getting caught on the diet for too long

Any investigative diet like the Low FODMAPS is only designed to be followed strictly for 4-6 weeks maximum to ensure your body doesn’t start to miss out on too many valuable food components (vitamins, minerals, anti-oxidants, fibre, prebiotics etc.) As you’ll read below, the negative impacts of following such a diet as a long-term symptom management strategy can outweigh the positives.

Some people are afraid to move off the diet out of worry for how they’ll feel. Getting the right guidance and support on this is extremely valuable.

  1. Dysbiosis in the large intestine

The risks of following a low FODMAPs diet. Cutting out FODMAPs foods may help reduce your gut symptoms, but it may starve your good bacteria too!

The reason that cutting out high-FODMAPs foods is so effective at reducing and even eliminating gut symptoms such as bloating, distension, flatulence, gassiness and tummy pain is because you’re not eating the foods that feed the range of bacteria living in our gut (namely prebiotics). When the bacteria in our large intestines feed off and ferment prebiotic foods, gases are produced. More on the importance of this soon.

Therefore a consequence of this diet is its impact on the microbiota – the different microorganisms living in our gut. We have many types of bacteria, yeasts, fungi and viruses living inside us, some of which are good and some not so good. The importance is in the balance and that we keep our ‘good’ microorganisms in greater quantity than the ‘bad’ to maintain a health gut environment.

Research reports that restricting our prebiotic (FODMAP) foods leads to the reduction in specific types of gut bacteria, including Bifidobacteria1. The take away message here is not to follow the strict low FODMAPs diet for any longer than required.

  1. If you starve your gut bacteria, they could start harming you

Sounds gross hey! I don’t mean to scare you. Our colon is lined with a protective mucous layer that serves as a habitat and food for some of our colonic bacteria. When there’s not enough fermentable fibre to go around, the more our mucus is relied on for their fuel.

Now, this is not a problem if we have lots of ‘good’ bacteria such as Lactobacilli and Bacteroidetes species to keep our gut health in check, as they could never eat enough of the layer to be a problem. However, without enough dietary fibre variety, they won’t be able to survive, and other types of undesirable bacterial strains can start thriving. Some of these bacteria can dissolve the mucus layer over time and if it gets too thin, we no longer have the protection needed. This can then result in sensitisation, inflammation and gut dysfunction2.   

On top of this, the building blocks of the mucous layer are called mucins, and their efficient production relies on short chain fatty acids such as butyrate3. These special fatty acids are produced by our ‘good’ colonic bacteria when they ferment FODMAPs! This is a keen reminder that following a low FODMAPs diet in the longtem may actually be harmful to your health.

The risks of following a low FODMAPs diet. Make sure you feed your good gut bacteria too
  1. Not getting the correct guidance from an experienced practitioner can impact your results

There is a lot of information on the internet and from downloadable apps that can guide you on how to cut out FODMAPs. However, my concern for people navigating a diet like this is how they then go about reintroducing foods once they feel better.

Also, has Dr Google given you enough guidance to come up with a suitable meal and snack plan to make the processes as easy and interesting as possible? Have they been given all the appropriate information and tips to interpret food labels, which can disguise FODMAPs unless you know what you’re looking out for? 

  1. Promotes food related anxiety and stress

Did you know that there is a strong relationship between anxiety/stress/worry and IBS symptoms4?! In fact, stress reducing activities such as meditation and mindfulness can be effective at improving gut symptoms and digestion.

Back to food now – any restrictive diet can trigger stress for some people – if this is you, please get support from an expert in the FODMAPs diet, so they can help this process be as easy and stress-free as possible for you. Reach out to me if you need.

  1. Low nutrient intake

As long as you are eating a variety of foods from the main food groups, your nutritional intake is likely to be fine. 

If you are avoiding or restricting major food groups there is an increased risk of missing out on some of the key nutrients like calcium. This is especially the case if you also have other food allergies or intolerances.

Nurture your gut and reintroduce FODMAPs foods back into your diet 

On the other hand, a dietitian experienced in gut health will help you to nurture your gut and your microbiome so that

  1. You can reintroduce FODMAPs foods comfortably and broaden your diet. This has an extra benefit that your expanded diet is helping to support your gut microbiome even more – a positive snow ball effect!
  2. Your healthier microbiome can support your health in other ways including
    • Reduce inflammation
    • Improve Mental health
    • Support a healthy weight
    • and much more (the list grows every day!)
  3. Having more foods in the diet will also help you to get in more healthy nutrients for overall health as well
  4. And of course you’ll be able to relax and enjoy social situations without worrying about limiting what you eat

If you’ve been following a low FODMAPs diet for more than 3 months its time to refocus to learn what you can do to introduce foods back into your day so you can eat more freely and enjoy food once again.

If you’re ready to embark on your gut-recovery journey click the button below to get started with our gut-focused dietitian.


  1. Staudacher & K. Whelan (2016). Altered gastrointestinal microbiota in irritable bowel syndrome and its modification by diet: probiotics, prebiotics and the low FODMAP diet; Proceedings of the Nutrition Society, Volume 75 Issue 3.
  2. Hansson (2013). Role of mucus layers in gut infection and inflammation, Curr Opin Microbiol. 2012 Feb; 15(1): 57–62.
  3. Finnie, et al. (1995). Colonic mucin synthesis is increased by sodium butyrate; Gut, Jan;36(1):93-9.
  4. H, Quin et al. (2014). Impact of psychological stress on irritable bowel syndrome; World J Gastroenterol. Oct 21; 20(39): 14126–14131.
Liz Beavis

Author Liz Beavis

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