A new randomized clinical trial comparing the Mediterranean diet and low-FODMAP diet in adult patients with diarrhea-predominant or mixed-type irritable bowel syndrome found that both diets reduced symptoms, but the low-FODMAP offered greater overall relief.
Researchers enrolled 26 patients aged 18 to 70 years who met Rome IV criteria for diarrhea-predominant or mixed-type irritable bowel syndrome. The participants were randomly assigned to follow either the Mediterranean diet (MD) or low-FODMAP diet (LFD) for 4 weeks. Meals and snacks were provided, and adherence was verified through food diaries reviewed by a gastrointestinal dietitian. The participants tracked symptoms daily and completed weekly validated symptom severity scales.
The primary endpoint was the proportion of patients with at least a 30% reduction in abdominal pain intensity (API) for at least 2 of the 4 weeks. Among those who completed the study, 80% of the participants in the MD group and 90% of those in the LFD group met this benchmark (P = 1.00). While the difference wasn't statistically significant, secondary measures favored the LFD.
The LFD group showed a greater reduction in IBS Symptom Severity Score (IBS-SSS) over 4 weeks (mean decrease = −105.5 vs −60, P = .02). More participants in the LFD group also met the IBS-SSS responder threshold (90% vs 50%) and reported adequate symptom relief (60% vs 30%), though these weren't statistically significant.
Exploratory outcomes showed greater improvement in discomfort, bloating, and quality of life in the LFD group. Anxiety scores, measured by the Generalized Anxiety Disorder-7, also declined more in the LFD group. The MD group showed symptom improvement, particularly in abdominal pain, but no statistically significant gains in bowel consistency or quality of life.
Both diets were generally well tolerated. Two participants withdrew as a result of side effects—one from each group—with one reporting abdominal pain on MD and the other reporting constipation on LFD. Overall adherence was high, averaging 94%.
The MD, rich in plant-based foods, healthy fats, and lean proteins, is known for its cardiovascular and metabolic benefits and shows moderate relief for IBS symptoms. However, in this study, the LFD—designed to reduce fermentable carbohydrates—was more effective in reducing symptom severity.
The study was a pilot feasibility trial and not powered for definitive conclusions. The researchers called for larger, real-world studies to evaluate long-term outcomes and determine whether the Mediterranean diet should be considered a routine treatment option for IBS.
The authors declared no conflicts of interest.
Source: Neurogastroenterology & Motility