Mediterranean diet and colorectal adenomas: a systematic review and meta-analysis of observational studies

Colorectal adenomas (CRAs) are epithelial lesions of the large bowel that can develop into colorectal cancer. Some studies have shown an inverse association of the Mediterranean diet (MED) with adenoma, but the extent of the association is equivocal. Owing to the lack of meta-analytical evidence in the literature, we sought to assess the association between MED and CRAs by conducting a systematic review and meta-analysis. A comprehensive systematic literature search of observational studies was conducted via PubMed, Scopus, Google Scholar and Web of Sciences up to May 2023. Studies were included in our review if they evaluated the association between MED and CRA, following an observational study design. Six studies were included in this study. We found that adherence to MED was inversely associated with CRA risk (odds ratio, 0.79; confidence interval, 0.73-0.85); implying that higher adherence to MED could reduce the risk of CRA by similar to 21%. Stratification by the year of studies, sex, study design, country and exposure showed a significant association between MED and CRA. The results of the current study provide evidence of an inverse association between adherence to MED and CRAs.