CATEGORY: GUT & DIGESTIVE HEALTH
The researchers had a modest goal. Their trial was built to show that a Mediterranean-style diet was no worse than the standard first-line dietary advice for irritable bowel syndrome. It cleared that bar and kept going. Among 139 UK adults followed for six weeks, 62% on the Mediterranean pattern got meaningful symptom relief against 42% on the usual advice, a gap of 20 people in every hundred, in a randomized trial published in Annals of Internal Medicine.1
A Common Disorder, and the Lever Reached For First
Irritable bowel syndrome is one of the most common digestive disorders. It brings recurring belly pain, bloating and unpredictable bowel habits, and diet is usually the first thing patients and clinicians turn to. The established dietary treatments mostly work by taking foods away. A Mediterranean diet does close to the opposite: vegetables, fruits, whole grains, beans, nuts and seeds, with olive oil as the main fat, regular fish and little red meat. The comparison arm got traditional dietary advice, the current first-line guidance of regular meal patterns, adequate fluids and limiting common trigger foods.
Six Weeks, a 500-Point Scale, and a Bar Set at 50
The 139 participants were adults aged 18 to 65, average age 40, about 80% of them women, which reflects how much more often the condition affects women. Their symptoms were active, averaging 309 points on the IBS Symptom Severity Scale. That questionnaire scores pain, bloating, bowel habit and how much daily life is disrupted, on a range from 0 to 500. A random draw, not a preference, sorted them: 68 to the Mediterranean pattern and 71 to traditional advice. After six weeks, a drop of 50 or more points counted as a clinical response, the size of change a patient can actually feel.
Twenty More Responders in Every Hundred
By that yardstick 62% of the Mediterranean group responded against 42% of the comparison group, and symptom scores fell further too, an average of 101 points against 65. Picture a hundred people with the condition trying each approach. About twenty more get real relief on the Mediterranean pattern than on the standard advice, a difference unlikely to be chance. Not everything moved in six weeks, and the paper says so. Mood, other bodily symptoms, quality of life and satisfaction with the diet showed no significant differences between the groups.
Where This Sits Beside the Elimination Diets
One trial sits inside a larger body of evidence. A 2025 network meta-analysis in The Lancet Gastroenterology & Hepatology pooled 28 randomized trials and 2,338 patients, found that several dietary approaches improved symptoms over habitual eating, and reported that the most accumulated evidence by far belongs to the low-FODMAP diet.2 That one is a short-term elimination approach. It strips out hard-to-digest fermentable carbohydrates found in foods like onions, garlic, wheat and certain fruits, then reintroduces them one by one, and it is demanding enough that a dietitian usually supervises it. The Mediterranean pattern adds foods rather than removing them, and it had little trial evidence behind it until now. 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 self-reported by nature.
Key Takeaways
- Six weeks on a Mediterranean-style diet brought meaningful symptom relief to 62% of adults with irritable bowel syndrome, against 42% on standard first-line dietary advice, with symptom scores falling 101 points against 65.
- The trial was designed only to show the Mediterranean diet was no worse than standard advice, and it came out better on the main measure. Mood, quality of life and diet satisfaction did not differ.
- Across 28 earlier randomized trials, the low-FODMAP elimination diet holds the most evidence in this condition. The Mediterranean pattern has far less, and six weeks cannot show how long a benefit lasts.
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