CATEGORY: GUT & DIGESTIVE HEALTH
Adults with irritable bowel syndrome who were assigned a Mediterranean-style diet were more likely to get meaningful symptom relief than those given the standard first-line dietary advice—62% versus 42%, a gap of 20 people in every hundred—in a six-week randomized trial of 139 UK adults published in Annals of Internal Medicine.1 Irritable bowel syndrome, one of the most common digestive disorders, brings recurring belly pain, bloating and unpredictable bowel habits, and diet is usually the first thing patients and clinicians reach for.
Designed to Prove “No Worse,” It Proved Better
The researchers’ stated goal was modest: the trial was built as a noninferiority study, designed to show that a Mediterranean-style diet was at least as good as the traditional advice. The result cleared that bar and kept going—the Mediterranean group did not merely match the standard approach but beat it, a difference unlikely to be chance (P=0.017). For a field where the established dietary treatments work by taking foods away, a simpler pattern holding its own was the hope; outperforming was the finding.
Six Weeks, Two Sets of Eating Habits
The 139 participants were adults aged 18 to 65—average age 40, about 80% women, reflecting how much more often irritable bowel syndrome affects women—with active symptoms averaging 309 points on the IBS Symptom Severity Scale, a standard questionnaire that scores pain, bloating, bowel habit and how much daily life is disrupted, from 0 to 500. Each person was assigned by chance, the design that lets a trial credit the diet itself rather than the people who chose it: 68 to a Mediterranean diet—an eating pattern built on vegetables, fruits, whole grains, beans, nuts and seeds, with olive oil as the main fat, regular fish, and little red meat—and 71 to traditional dietary advice, the current first-line guidance of regular meal patterns, adequate fluids and limiting common trigger foods. After six weeks, a drop of 50 or more points on the symptom scale counted as a clinical response, the difference a patient can actually feel.
Twenty More Responders in Every Hundred
By that yardstick, 62% of the Mediterranean group responded versus 42% of the comparison group, and symptom scores fell further too—an average drop of 101 points against 65. Picture a hundred people with irritable bowel syndrome trying each approach: about twenty more of them get real relief on the Mediterranean pattern than on the standard advice. Not everything moved in six weeks, and the paper says so: measures of mood, other bodily symptoms, quality of life and satisfaction with the diet showed no significant differences between the groups. The gut symptoms improved; the broader measures had not yet followed.
Where This Sits in the Diet Toolbox
Because this was a randomized trial, the comparison carries real weight—but it is one trial, and it sits inside a larger body of evidence. A 2025 network meta-analysis in The Lancet Gastroenterology & Hepatology, pooling 28 randomized trials with 2,338 patients, found that several dietary approaches improved symptoms over habitual eating, and that the most accumulated evidence by far belongs to the low-FODMAP diet—a short-term elimination approach that strips out hard-to-digest fermentable carbohydrates found in foods like onions, garlic, wheat and certain fruits, then reintroduces them one by one.2 The Mediterranean pattern, by contrast, had little trial evidence behind it; this study adds a piece. The practical distinction is real: an elimination diet works by subtraction, is demanding to follow and is usually run with a dietitian’s supervision, while the Mediterranean pattern is a single familiar way of eating that adds foods rather than removing them. The authors were candid about the limits—six weeks is long enough to measure a response but not to know whether it lasts, and symptom scales are, by nature, self-reported.
Key Takeaways
- In a six-week randomized trial, 62% of adults with irritable bowel syndrome on a Mediterranean-style diet got meaningful symptom relief, versus 42% with standard first-line dietary advice—about 20 more responders per hundred people.
- The trial was designed only to show the Mediterranean diet was no worse than standard advice; it turned out better on the main measure.
- Across 28 earlier randomized trials, the low-FODMAP elimination diet holds the most evidence in irritable bowel syndrome; the Mediterranean pattern has far less, and this trial strengthens its case.
- Six weeks can show a response but not durability—how well the benefit holds up long term is not yet known.
References
- Bamidele JO, Brownlow GM, Flack RM, et al. The Mediterranean Diet for Irritable Bowel Syndrome: A Randomized Clinical Trial. Annals of Internal Medicine. 2025;178(12):1709–1717. link
- Cuffe M, Staudacher HM, Aziz I, et al. Efficacy of dietary interventions in irritable bowel syndrome: a systematic review and network meta-analysis. The Lancet Gastroenterology & Hepatology. 2025;10(6):520–536. link