The Mediterranean Diet wins again – this time in IBS!
Review by Prof. Eamonn Quigley (USA)
Study Summary
Our IBS patients have been telling us for decades that food ingestion (along with stress and the menstrual cycle, in females) is one of the main triggers of symptom onset or exacerbation in irritable bowel syndrome (IBS) but this information was largely ignored. Now, gastroenterologists and clinician scientists have woken up and the role of foods and diets in IBS has emerged as a major field of research. While the contributions of classical IgE-related food allergies to IBS appear to be minimal, it has become evident that intolerances to various foods are prevalent with symptoms generated by incomplete digestion of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) being especially common. Thus, the widespread advocacy, supported by a considerable volume of clinical trial evidence, of the low FODMAP diet in IBS. This diet is complex to follow and challenging to adhere to, leading to explorations of other diets. Among these, evidence suggesting a lower prevalence of IBS among those who regularly consumed a Mediterranean diet led to a small pilot study which showed promise and, ultimately, to this randomized trial from the University of Sheffield in the UK. 139 individuals with IBS defined according to Rome IV criteria (regardless of subtype) were randomized to either traditional dietary advice (according to guidance developed by the British Dietetic Association) or a Mediterranean diet for 6 weeks. Both clinical response rates (62% vs 42%) and mean reduction in IBS symptom severity scale (-101.2 vs -64.5) were significantly greater among those on the Mediterranean diet compared to those on the traditional diet. Response rates were unaffected by IBS subtype.
Commentary
Dietary studies are traditionally challenging to design and complete, thereby underscoring the significant accomplishment of these researchers. Traditional dietary advice included promoting sensible eating habits, as well as avoiding excess fatty and spicy foods, processed foods, caffeine, carbonated beverages, and alcohol. In contrast, the Mediterranean diet featured fruit, vegetables, pulses, whole grains, nuts, fish, and olive oil. It needs to be stressed that there are many variants of a Mediterranean diet with olive oil being a critical component of all. Whether some Mediterranean diets are more effective than others in IBS remains to be defined. It should also be stressed that the study lasted for just 6 weeks – a very brief interlude in the life of an IBS sufferer. We look forward to longer term data on efficacy. While, at this time, the Mediterranean diet does not have the same evidence base as the low-FODMAP diet, a growing consensus on the benefits of this diet to overall health may well move it to being the preferred dietary option in the overall management of IBS. It is also interesting to note that some of the components of the Mediterranean diet would be excluded in a low-FODMAP diet; does this mean that there may be different populations who respond to one dietary intervention over the other? Only a high-quality head-to-head trial will provide the answer. Similarly, the mode of action of the Mediterranean diet in IBS remains unknown; could the known anti-inflammatory or microbiome-modulating effects of this dietary change be relevant? Only time will tell.
Citation
https://pubmed.ncbi.nlm.nih.gov/41144975/
Bamidele JO, Brownlow GM, Flack RM, Buckle RL, Shaw CC, Shiha MG, Aziz I. The Mediterranean Diet for Irritable Bowel Syndrome : A Randomized Clinical Trial. Ann Intern Med. 2025 [epub ahead of print].
View past News You Can Use commentaries
