Mediterranean diet may be effective for managing IBS

1. In this randomized clinical trial, a higher percentage of adults following a Mediterranean diet achieved clinical response to irritable bowel syndrome (IBS) compared with adults following traditional dietary advice.

2. A Mediterranean Diet was also associated with better diet adherence.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Up to one-tenth of the population is affected by irritable bowel syndrome (IBS), which is usually initially managed through diet. However, evidence on effective dietary options for IBS remains lacking, with only 40% of individuals responding to traditional dietary advice (TDA) and many being escalated to the low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) diet, which may be complex or costly or pose challenges in social contexts. Studies have shown an association between a Mediterranean Diet (MD) and reduced IBS prevalence as well as improved IBS symptoms. This study aimed to determine whether an MD is non-inferior to TDA in managing IBS symptoms. After six weeks, nearly two-thirds of individuals assigned an MD achieved clinical response, defined as a fifty-point or greater reduction on the IBS Symptom Severity Scale (IBS-SSS), compared with less than half of individuals assigned TDA. Furthermore, nearly half of individuals assigned an MD achieved a 100-point or greater reduction as opposed to less than one-third of individuals assigned TDA. The mean point reduction was greater among MD participants compared with TDA participants. The frequency of abdominal pain was found to be significantly improved among the MD group versus TDA. Both groups were similarly satisfied with their diets, but individuals following an MD had better adherence. Subgroup analysis showed that participants with moderate IBS also had a significantly higher response to the MD compared with TDA. The generalizability of this study is limited by lack of blinding, a short study period, and a limited age range. Nevertheless, this study suggests that a Mediterranean Diet may be effective in controlling IBS.

Click to read this study in AIM

Relevant Reading: Clinical trial: A Mediterranean diet is feasible and improves gastrointestinal and psychological symptoms in irritable bowel syndrome

In-Depth [randomized controlled trial]: This randomized controlled trial aimed to compare an MD and TDA for managing IBS symptoms. Patients were included if they were aged 18 to 65 years, fulfilled the Rome IV diagnostic criteria for IBS, and scored 75 or higher on the IBS-SSS. Patients were excluded if they had a body mass index (BMI) less than 20 kg/m², a history of eating disorders, or a number of other conditions such as inflammatory bowel disease, celiac disease, or poorly controlled diabetes. The primary outcome was the proportion of each group that achieved clinical response, represented by a 50-point or greater reduction on the IBS-SSS. This study randomly assigned 168 participants, 86 of whom were assigned to an MD and 82 to TDA. The modified intention-to-treat (modified-ITT) analysis included 139 participants, 68 of whom were in the MD group and 71 in the TDA group. The per protocol analysis included 110 participants, 56 in the MD group and 54 in the TDA group, who had adequately followed the diet assigned to them. The cohort had a mean age of 40.4 years (range, 19 to 65 years), with 80% of participants being women and 92% being White. The modified-ITT analysis showed that at week 6, 42 of 68 patients (62% [95% CI, 50% to 73%]) assigned an MD and 30 of 71 patients (42% [95% CI, 31% to 55%]) assigned TDA achieved a 50-point or greater reduction in IBS-SSS; this yielded a risk difference of 20 percentage points (95% CI, 4 to 36 percentage points) in favor of the MD. A 100-point reduction in IBS-SSS was achieved by 44% (30 of 68 [95% CI, 32% to 57%]) assigned an MD versus 32.4% (23 of 71 [95% CI, 22% to 45%]) assigned TDA; this yielded a risk difference of 13 percentage points (95% CI, -3 to 29 percentage points) in favor of the MD. A greater reduction in the mean IBS-SSS was seen after an MD compared with TDA (-101.2 vs. -64.5; difference = -36.7 [95% CI, -70.5 to -2.8]; p = 0.034). Both groups had similar diet satisfaction, but the MD group had a significantly greater change in dietary adherence score (MEDAS) at week 6 (5.1 to 8.9; difference = 3.8) versus TDA (4.6 to 5.8; difference = 1.2) (p <0.001). Subgroup analysis showed that significantly more participants with moderate IBS had a response to an MD compared with those receiving TDA (70% [16 of 23] vs. 38% [11 of 29]; p = 0.02). Overall, this study suggests that an MD may be associated with superior management of IBS symptoms as well as diet adherence compared with TDA.

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