THE FODMAP DIET

WHAT, WHY, HOW

By Brooke Penney, Dietitian

If you do a Google search for a diet to help improve gut symptoms, the list of options will be truly endless. There is however an eating pattern that is a cut above the rest. The diet with the most science behind it is the low FODMAP diet, developed by Monash University (Bellini & Rossi 2020, Halmos & Gibson 2019). Research shows that 3 in 4 people with irritable bowel syndrome will see an improvement in their symptoms after following the low FODMAP diet (Muir & Gibson 2013). The symptom relief can be quite substantial, so much so that studies have also shown a significant improvement in quality of life after following the diet (Schumann et al.) Research looking specifically at the low FODMAP diet in children follows similar patterns. Studies have shown reductions in abdominal pain (Turco et al., 2018, Chumpitazi et all., 2015) and significant improvements in gut symptoms related to functional bowel disorders in children (Brown et al., 2020). 

So if the results are so positive, why can’t my child stay on the low FODMAP diet forever? 

Firstly, let’s look at what the low FODMAP diet is. FODMAP stands for Fermentable Oligo-, Di- and Mono-saccharides and Polyols. These are a group of 6 carbohydrate chains and sugar alcohols that are found in a huge range of foods. Their key characteristic is that they are difficult for the body to digest. They draw water into the intestine and can affect the speed at which food moves through the digestive system. Once into the lower bowel, these FODMAP’s are rapidly fermented by our good bacteria. This fermentation is a totally normal final stage of digestion, however the bacteria produce large amounts of gas in the process. Some people can eat FODMAP containing foods without any issues, but for others these digestive processes can result in a range of annoying and uncomfortable symptoms, including diarrhea, constipation, excessive bloating and wind, and abdominal pain (Gibson & Shepard et al., 2010). 

The FODMAP diet itself involves 3 phases, the first of these is the low FODMAP phase. This phase is what people are commonly referring to when they say ‘the low FODMAP diet’. This phase involves swapping foods that are high in FODMAPs for lower FODMAP alternatives for 4-6 week period (Tuck and Barret 2017.) If this phase leads to an improvement in symptoms, it indicates there is a sensitivity to at least 1 of the 6 FODMAP groups. 

The next phase involves a series of specific food challenges. Certain high FODMAP foods will be reintroduced into the diet while carefully observing the intensity of the symptoms that follow. The purpose of this reintroduction phase is to identify which FODMAP types are your individual triggers, as well as what serve sizes can be tolerated. With this knowledge, the final stage is to expand the diet as much as possible to create an individualised, long term diet. This is called the personalisation phase (Barrett 2017). 

The Low FODMAP phase is designed to be short term 

The progression to this personalistion phase is a key reason why following the low FODMAP phase long term is just not necessary. It is unlikely that your child will be highly sensitive to all 6 FODMAP groups, with the type of FODMAP and serve size tolerated differing from person to person. The ultimate aim is to bring as many high FODMAP foods back into the diet as possible, unwinding the restriction while maintaining control of your symptoms (Tuck and Barrett 2017). Continuing the first stage of the diet may keep symptoms well under control, but it is very likely that you will be avoiding foods that are perfectly okay for you to eat!  

Things to Consider

Nutritional issues 

The long-term restriction needed during the low FODMAP phase can lead to problems with nutrition. Having to eliminate all high FODMAP foods can make it more difficult to consume adequate amounts of key nutrients, namely carbohydrates, fibre, antioxidants and calcium (Hill et all 2017, Halmos, E. P., and Gibson, P. R. 2019). Children on the low FODMAP diet have also been shown to eat fewer calories when compared to those who are not on the diet (Costa et al, 2020).  

Effect on the gut microbiome 

Following the low FODMAP phase long term can affect our gut microbiome, the collection of good bacteria that live in our digestive system and ferment our food. A number of FODMAP containing foods are classed as prebiotics, ie: “gut bacteria food”. If there are less prebiotics available for the good bacteria to ferment, the number of good bacteria in our gut can start to decrease (Hill et al., 2017, Staudacher 2012, Halmos and Gibson 2019). 

Difficulty in following the diet long term 

All 3 phases of the FODMAP diet are difficult to manage, but the low FODMAP phase is particularly tricky! The broad range of foods that need to be avoided during this phase can be quite challenging, especially in children’s diets. In fact, it is recommended that young children follow a simplified version of the low FODMAP phase to avoid restricting the diet too much, as this may negatively affect their eating habits (Halmos and Gibson 2019).  

 The FODMAP diet’s 3 phases were designed to be completed in their entirety. While the symptom improvement the low FODMAP phase can provide can be a very welcome relief, it is important not to stop here and continue through the next 2 phases to avoid the negative effects of long term restriction. [

A FINAL NOTE

It is vital to carefully consider whether the FODMAP diet is right for your child. There are many reasons why children experience gut symptoms so it is essential that you consult your GP to identify any underlying issues that need to be addressed. The low FODMAP is also not the only treatment option available for gastrointestinal issues. There may be an alternate, possibly simpler approach that will resolve the troublesome symptoms so always consult with your GP or dietitian before commencing the FODMAP diet. 

REFERENCES

Barrett, J. S. (2017) How to institute the low-FODMAP diet. Journal of Gastroenterology and Hepatology, 32: 8– 10. 

Brown, S.C., Whelan, K., Gearry, R.B. and Day, A.S. (2020), Low FODMAP diet in children and adolescents with functional bowel disorder: A clinical case note review. JGH Open, 4: 153-159. z

Chumpitazi BP, Cope JL, Hollister EB, Tsai CM, McMeans AR, Luna RA, Versalovic J, Shulman RJ. (2015) Randomised clinical trial: gut microbiome biomarkers are associated with clinical response to a low FODMAP diet in children with the irritable bowel syndrome. Aliment Pharmacol Ther. 42(4):418-27. 

Schumann, D., Klose, P., Lauche, R., Dobos, G., Langhorst, J. and Holger Cramer (2018) Low fermentable, oligo-, di-, mono-saccharides and polyol diet in the treatment of irritable bowel syndrome: A systematic review and meta-analysis. Nutrition. 45: 24-31.

Gibson, P.R. and Shepherd, S.J. (2010), Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology, 25: 252-258. 

Halmos, E. P., and Gibson, P. R. (2019) Controversies and reality of the FODMAP diet for patients with irritable bowel syndrome. Journal of Gastroenterology and Hepatology, 34: 1134– 1142. 

Halmos EP, Christophersen CT, Bird AR, Shepherd SJ, Gibson PR, Muir JG (2015) Diets that differ in their FODMAP content alter the colonic luminal microenvironment Gut 64:93-100. 

Staudacher HM, Lomer MC, Anderson JL, Barrett JS, Muir JG, Irving PM, Whelan K. (2012) Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. J Nutr. 142(8):1510-8. 

Tuck, C., and Barrett, J. (2017) Re-challenging FODMAPs: the low FODMAP diet phase two. Journal of Gastroenterology and Hepatology, 32: 11– 15.