Article information
Authors: Kevin Whelan, Alexander C Ford, Helen Burton-Murray, Heidi M Staudacher
Journal: The Lancet Gastroenterology & Hepatology
Year: 2024
Volume: 9
Pages: 1147–1161
DOI: 10.1016/S2468-1253(24)00238-3
Study at a glance
- Study type: Narrative review
- Focus: Clinical evidence, challenges, burdens, and risks of dietary management strategies in irritable bowel syndrome (IBS)
- Interventions reviewed: Dietary supplements (fibres, prebiotics), individual foods (kiwifruit, fermented foods), and whole-diet interventions (low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols [FODMAP] diet, British Dietetic Association [BDA] and National Institute for Health and Care Excellence [NICE] dietary advice, gluten-free diet, Mediterranean diet)
- Key considerations: Patient demographics, food cost and availability, acceptability of dietary management, impact on food-related quality of life, eating disorder risk, and optimal delivery approaches in health care settings
Why was this study done?
Irritable bowel syndrome (IBS) affects around 4.1% of people worldwide, causing recurring abdominal pain alongside changes in how often you go to the toilet or in the consistency of your stools.
Diet has become central to managing IBS, driven both by growing research and by many people’s preference for lifestyle management options other than medication. Whelan and colleagues set out to summarise the evidence for dietary management in IBS, understand the difficulties and risks, and suggest how to handle them in practice.
How was the study performed?
The authors searched the main medical research database using terms such as ‘irritable bowel syndrome’, ‘diet’, ‘nutrition’, ‘education’, ‘psychology’, and ‘eating and feeding disorder’, focusing on English-language studies most relevant to current practice. They added key papers from their own collections and, where research was limited, drew on their combined expertise in gastroenterology, dietetics, and eating disorder psychology.
What did the researchers find?
Supplements
Pooling 14 randomised trials showed that ispaghula husk (psyllium) helped IBS overall, whereas wheat bran was no better than placebo. A similar analysis of 11 trials found prebiotics were no better than placebo for improving symptoms overall.
Individual foods
High-fibre foods improved symptoms, but no more than low-fibre comparison foods. Fermented foods helped compared with baseline, but offered nothing extra over their unfermented versions. Two trials of green kiwifruit (two a day) in constipation-predominant IBS found people went more often, but again no more than with psyllium or placebo.
Whole-diet interventions
Comparing 13 trials together, the low-FODMAP diet ranked first and outperformed the other diets for easing symptoms overall. Standard British Dietetic Association and NICE advice ranked second, though it was not clearly better than any other approach.
The evidence for a gluten-free diet rested on just two randomised trials, and once combined the effect was not statistically significant, most likely because the studies were too different to compare reliably. Small Mediterranean diet trials reported good adherence and symptom improvement, but larger, more rigorous trials are still needed.
Challenges and risks identified
Some approaches rely on special products that cost noticeably more. Gluten-free bread was four times the price of ordinary bread, and in one trial 82% of people said the low-FODMAP and gluten-free diets cost more than their usual diet.
People with IBS also got less enjoyment from food than healthy people, and even than people with other chronic illnesses. Studies of eating disorders in adults with IBS reported that 2% to 29% may currently have one, with 9% to 17% diagnosed at some point. A large study in Taiwan found a seven-times higher risk of anorexia nervosa in adults with IBS than in healthy people, though the actual number of cases was very small and the authors caution the figure is uncertain because of how diagnoses were recorded.
Delivery of dietary interventions
Most trials were run by dietitians. Advice from a dietitian worked better than written leaflets, while a mobile app produced results similar to seeing a dietitian in person. Even so, although 96% of NHS trusts in England offered general dietitian services for IBS, only about half had a dietitian specifically responsible for IBS diets. Group education worked about as well as one-to-one appointments, at lower cost.
What did the authors conclude?
Diet is a cornerstone of IBS management, but real gaps in the evidence remain, particularly around supplements, the best way to deliver stricter diets, and how well the gentler, less restrictive diets work. Before recommending any diet, clinicians should weigh up the many personal and practical factors that shape how someone eats. Getting this wrong, or not monitoring closely, can leave people short on nutrients, worsen or even trigger disordered eating, and take the pleasure out of food. In short, we still need a clearer picture of which diets help, who they help, and how to offer them safely.
Key takeaways
- Some dietary changes genuinely help in IBS, and among the whole-diet approaches the low-FODMAP diet has the strongest evidence.
- Stricter diets can be hard to deliver safely, and cost, availability, how liveable they are, and their effect on the enjoyment of food all matter.
- Disordered eating is relatively common in people with IBS, raising the concern that restrictive diets could add to that risk.
- Access to specialist dietitians varies considerably, and group sessions look promising as a lower-cost option.
- Key questions remain about the best way to deliver these diets, who is most likely to benefit, and whether restrictive approaches are safe over the long term.
This Scientific Publication Summary is an objective summary of the published study for personal and educational use. It does not constitute medical advice, endorsement of the intervention, or a recommendation to alter clinical practice.