The Mediterranean diet and risk of colorectal cancer in the UK women's cohort study

Background: Evidence from epidemiological studies investigating associations between adherence to the Mediterranean diet and colorectal cancer is inconsistent. The aim of this study is to assess whether adherence to the Mediterranean dietary pattern is associated with reduced incidence of cancers of the colon and rectum in the UK Women’s Cohort Study. Method: A total of 35 372 women were followed for a median of 17.4 years. A 10-component score indicating adherence to the Mediterranean diet was generated for each cohort participant using a 217-item food frequency questionnaire. The Mediterranean diet score ranged from 0 for minimal adherence to 10 for maximal adherence. Cox proportional hazards regression was used to provide adjusted hazard ratios (HR) and 95% confidence intervals (CI) for colon and rectal cancer risk. Results: A total of 465 incident colorectal cancer cases were documented. In the multivariable-adjusted model, the test for trend was positive (HR=0.88, 95% CI: 0.78 to 0.99; Ptrend = 0.03) for a 2-point increment in the Mediterranean diet score. For rectal cancer, a 2-point increment in the Mediterranean diet score resulted in an HR (95% CI) of 0.69 (0.56 to 0.86) whilst a 62% linear reduced risk (HR 0.38; 95% CI: 0.20 to 0.74; Ptrend < 0.001) was observed for women within the highest vs. the lowest category of the MD score. Estimates for an association with colon cancer were weak (Ptrend = 0.41). Conclusion: Findings suggest women adhering to a Mediterranean dietary pattern may have a lower risk of colorectal cancer, especially rectal cancer.