One important therapy for managing functional gastrointestinal disorders such as irritable bowel syndrome (IBS) is diet, in which modulating the gastrointestinal microbiome probably plays a role.

More than 80% of patients with IBS report a key role for diet as a trigger of symptom generation, leading them to explore a wide range of dietary interventions to help alleviate their symptoms. Wheat components, including fructans, gluten, wheat germ agglutinins and alpha-amylase trypsin inhibitors, have been identified as being involved in symptom generation. However, not all diets promoted in newspapers and blogs and on social media are supported by scientific evidence.

Randomized controlled trials suggest that gluten-free diets and low FODMAP diets may improve IBS symptoms, particularly in the short term. Of those, the low FODMAP diet, which originated in Australia, has been recommended by certain guidelines for treating symptoms in some IBS patients, following first-line dietary advice focusing on adopting healthy eating habits.

Briefly, FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These are short-chain carbohydrates and sugar alcohols found in a wide range of foods and food additives that are poorly absorbed by the body, resulting in bloating, gas and abdominal pain via osmotic overload, bacterial fermentation or changes in gut microbiota composition.

Despite its clinical effectiveness, the low FODMAP diet presents a number of challenges. For instance, it can alter gut microbiota composition, with a marked reduction in bifidobacteria and a reduced total bacterial count; it can affect nutrient intake and diet quality (especially if used in the long term); it requires the patient to be adequately supported by a registered dietitian to follow the diet accurately and safely; and not all patients respond to the diet.

A new review co-authored by Bridgette Wilson, Selina R. Cox and Kevin Whelan from King’s College London updates challenges linked to following the low FODMAP diet and suggests science-based approaches in order to minimize them.

The current science-based approaches to minimizing the challenges of the low FODMAP diet in clinical practice, preferably implemented by a registered dietitian specializing in gut health, are summarized below.


Challenges of the low FODMAP diet Guidance for overcoming them
Altered gut microbiota composition.
  • Incorporate a bifidobacteria-containing probiotic during the first restriction stage of the low FODMAP diet.
  • Undergo structured and personalized reintroduction of FODMAP-rich foods (ensure the period spent following the first stage is as short as possible).
Compromised nutrient intake (i.e. fiber, iron and calcium) and diet quality.
  • Optimize intakes of calcium- and iron-rich foods during the restriction stage of the low FODMAP diet.
  • Gradually optimize dietary fiber intake (preferably from food sources) without worsening gut symptoms.
Difficulties with adherence (due to the need for extensive label-reading abilities, high cost of foodstuffs low in FODMAPs and fewer social activities, among others).
  • The first-line dietary advice in patients with IBS is to follow healthy eating advice. Only when that is unsuccessful in resolving symptoms can the low FODMAP diet be tried with registered dietitian support.
  • Naturally FODMAP-free foods should be encouraged over specialist products in the context of a balanced diet.
Getting caught on the low FODMAP diet for too long and without the supervision of a registered dietitian.
  • The personalized support of a registered dietitian specializing in gut health is necessary to better follow the low FODMAP diet without incurring in nutritional deficits.
  • Supplementary tools such as recipe books and mobile applications cannot replace dietetic advice.
Up to 50% of patients do not respond to the low FODMAP diet.
  • While the baseline gut microbiota is being explored as a means of predicting the clinical response to a low FODMAP diet, no tests are currently available in routine clinical practice to determine individual response to the low FODMAP diet.

On the whole, although the low FODMAP diet has been shown to be effective in improving overall and specific symptoms in 50% to 80% of patients with IBS, the diet is not without adverse effects that can be minimized with personalized support by a gastro dietitian. Optimizing nutrient intake from natural food sources while maintaining diet quality and contemplating including a probiotic to minimize the detrimental effect on gut-dwelling bifidobacteria are both important points for consideration when patients with IBS follow the low FODMAP diet.



Rej A, Aziz I, Sanders DS. Personalizing dietary therapies for irritable bowel syndrome: what is gluten’s role? Clin Gastroenterol Hepatol. 2020. doi: 10.1016/j.cgh.2020.10.024.

Staudacher HM, Scholz M, Ce Lomer M, et al. Gut microbiota associations with diet in irritable bowel syndrome and the effect of low FODMAP diet and probiotics. Clin Nutr. 2020. doi: 10.1016/j.clnu.2020.10.013.

National Institute for Health and Care Excellence (2017) NICE (2017 update): irritable bowel syndrome in adults: diagnosis and management (NICE guidelines CG61) [NIfHC Excellence, editor]. Available from: [accessed 8th April 2021].

Valdez-Palomares F, Nambo-Venegas R, Uribe-García J, et al. Intestinal microbiota fingerprint in subjects with irritable bowel syndrome responders to a low FODMAP diet. Food Funct. 2021. doi: 10.1039/D0FO03162C.

Wilson B, R Cox S, Whelan K. Challenges of the low FODMAP diet for managing irritable bowel syndrome and approaches to their minimization and mitigation. Proc Nutr Soc. 2021; 80(1):19-28. doi: 10.1017/S0029665120006990.