Mediterranean dietary components are inversely associated with advanced colorectal polyps: A case-control study

AIM To evaluate the association between the Mediterranean diet (MD) pattern and its components, and advanced colorectal polyps (adenoma and serrated adenoma). METHODS A case-control study among patients undergoing screening, diagnostic or surveillance colonoscopies during 2010-2015 at the Tel-Aviv Medical Center, Gastroenterology Department. Cases with advanced polyps were defined as: Advanced adenoma [> 10 mm, with features of high grade dysplasia (HGD) or villous histology], advanced serrated adenoma (> 10 mm or with dysplasia) or multiple (>= 3) non-advanced adenomas or serrated adenomas. Cases of non-advanced adenomas were defined as adenomas < 10 mm, without features of HGD or villous histology. Controls were defined as those without polyps at the current colonoscopy and without a history of colorectal polyps. Data collection included: anthropometrics measured according to a standardized protocol, fasting blood tests performed at the same lab, medical history recorded by a structured interview and dietary intake evaluated by a 116-item food frequency questionnaire. Adherence to the MD components was evaluated according to intake above/below the sample median, for potentially beneficial/detrimental components respectively, as accepted. RESULTS We recruited 206 cases with advanced polyps, 192 cases with non-advanced adenoma and 385 controls. The number of adhered MD components was inversely associated with a diagnosis of advanced polyps in a dose-response manner (OR = 0.34, 95%CI: 0.17-0.65; OR = 0.22, 95%CI: 0.11-0.43; and OR = 0.18, 95%CI: 0.07-0.47 for 3-4, 5-7 and 8-10 components, respectively), but not with non-advanced adenomas (OR = 0.54, 95%CI: 0.25-1.13; OR = 0.48, 95%CI: 0.23-0.99; and OR = 0.43, 95%CI: 0.16-1.12 for 3-4, 5-7 and 8-10 components, respectively). Low intake of sugar-sweetened beverages and red meat, as well as high intake of fish, were inversely associated with advanced polyps (OR = 0.56, 95%CI: 0.36-0.87; OR = 0.63, 95%CI: 0.42-0.95; and OR = 0.66, 95%CI: 0.44-0.99, respectively), while only low intake of red meat was inversely associated with non-advanced adenomas (OR = 0.71, 95%CI: 0.49-0.97). CONCLUSION A better adherence to the MD, specifically low intake of sugar-sweetened beverages and red meat as well as high intake of fish, is related to lower odds for advanced polyps.