The risks of following a low FODMAPs diet

By March 1, 2018Restore Your Gut

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

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. 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 reason 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 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!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! The key message here is to eat some of the ‘moderate’ FODMAP foods that are suitable on the diet each day, to provide some (yet portioned) food for your good bacteria – please ask your Dietitian if you don’t know which these are. Some supplementary fibres such as Partially Hydrolysed Guar Gum are also highly beneficial and well tolerated.

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, are they given 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. The risk of missing out on some of the key nutrients like calcium will come from having to eliminate whole food groups due to other dietary needs like allergies or food intolerances or not knowing how to swap high FODMAP foods with low options of similar key nutrients.


If you’re ready to embark on the journey to discover what triggers your IBS symptoms please get in touch. Or if you have been following any type of restricted diet for a while without any support, please definitely get in touch.

Hope this helps – Amanda Moon, APD



  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.
Amanda Moon

Author Amanda Moon

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