Mediterranean diet shows no significant protection against prostate cancer in meta-analysis

A systematic review and meta-analysis of observational studies has found no statistically significant difference in prostate cancer risk between men with high and low adherence to the Mediterranean diet. The pooled analysis, published in BMC Nutrition, combined data from fourteen studies identified through searches of PubMed, Web of Science, and Scopus, and applied a random-effects model with REML estimation and Hartung–Knapp adjustment. The resulting relative risk was 0.98, with a 95 percent confidence interval of 0.93 to 1.04, a range that includes the null value of 1.0 and therefore does not support a protective association.

Prostate cancer is the most common malignancy among men worldwide, and while some risk factors cannot be modified, lifestyle factors have drawn increasing attention in prevention research. The Mediterranean diet, characterized by high intake of plant-based foods, unsaturated fatty acids, and antioxidant micronutrients, has been proposed as a dietary pattern that might lower cancer risk. The new analysis set out to test that proposition systematically by examining associations between adherence to the diet and prostate cancer risk across the eligible observational literature.

Heterogeneity across studies was assessed using I² and τ² statistics, and the pooled estimate showed moderate heterogeneity, with a Q statistic of 19.95 and I² of 34.8 percent. Publication bias was evaluated using a funnel plot, a contour-enhanced funnel plot, and Egger’s regression test.

Egger’s test did not indicate statistically significant publication bias, returning a p value of 0.115. However, the authors noted that complementary analyses, including a Q-Q plot and a limit meta-analysis, suggested a possible small-study effect. The authors concluded that this possibility warrants cautious interpretation of the pooled estimate.

The overall conclusion of the meta-analysis was that no protective effect of the Mediterranean diet against prostate cancer was found. The authors nevertheless pointed to biological plausibility and inconsistent epidemiological trends as reasons to continue investigating the question. They called for further research using standardized dietary assessments and incorporating genetic and microbiome-related factors.

The review protocol was not prospectively registered.

The study was published as an open access article in BMC Nutrition on 4 November 2026, with the review shared early to provide faster access to peer-reviewed, accepted research. The authors were Tom Thabo Jahnke, Christian Holschuh, and Peter Schlattmann.

Subject of Research: Association between Mediterranean diet adherence and prostate cancer risk, examined through a systematic review and meta-analysis of observational studies

Article Title: Mediterranean diet and risk of prostate cancer: a systematic review and meta-analysis of observational studies

Article References: Jahnke, T. T., Holschuh, C., & Schlattmann, P. (2026). Mediterranean diet and risk of prostate cancer: a systematic review and meta-analysis of observational studies. BMC Nutrition, 12(1), Article 234. https://doi.org/10.1186/s40795-026-01544-5

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DOI: 10.1186/s40795-026-01544-5

Keywords: Mediterranean diet, prostate cancer, meta-analysis, systematic review, observational studies, dietary patterns, cancer prevention, BMC Nutrition, publication bias, random-effects model, Mediterranean, diet