Question: Does adherence to a Mediterranean diet improve total mortality, as well as mortality due to coronary heart disease (CHD) and cancer?
Population: Men and women aged 20 86 years from all geographic areas within Greece. Subjects having CHD, cancer, and diabetes mellitus at the time of enrollment were excluded.
Design and methods: A cohort of 28 572 participants was recruited as part of the European Prospective Investigation into Cancer and Nutrition (EPIC) and 22 043 were followed prospectively for a median duration of 44 months. Baseline measurements of diet were obtained using a validated semi-quantitative food-frequency questionnaire, and adherence was determined using an aggregate 10-point scale (from zero to nine, indicating greater adherence with increasing score) devised a priori to incorporate nine prominent components of the traditional Mediterranean diet. A binary value was assigned based on the relative consumption of presumed beneficial or detrimental components. Participants whose consumption of beneficial components (vegetables, legumes, fruits and nuts, cereal, fish, ratio of monounsaturated to saturated fats) was above sex-specific medians were assigned a score of one. Participants whose consumption was below-median were assigned a score of zero. Detrimental components (meat and poultry, dairy) were scored in the opposite fashion -participants whose consumption was above-median were assigned a score of zero, and participants whose consumption was below-median were assigned a score of one. Scoring of alcohol intake was based on whether consumption was within beneficial sex-specific consumption ranges (males, 10 50 g per day; females, 5 25 g per day). Cause of death was obtained from death certificates and official records, and was classified by physicians blinded to diet score. Cox proportional hazards regression models were used to measure the association between studied food groups, adherence to the Mediterranean diet and mortality after adjustment for age, sex, energy expenditure, smoking status, anthropomorphic measures, and other confounding factors.
Results: Over the follow-up period, 81 139 person-years were accrued and 275 deaths were recorded. Adherence to the Mediterranean diet was inversely related to mortality. A two-point increase in the aggregate score resulted in an adjusted hazard ratio for death of 0.75 (95% confidence interval [CI], 0.64 to 0.87). Mortality due to CHD (adjusted hazard ratio, 0.67 [95% CI, 0.47 to 0.94]) and mortality due to cancer (adjusted hazard ratio, 0.76 [95% CI, 0.59 to 0.98]) were also inversely associated with a two-point increase in the aggregate score. Consumption of individual food components in the Mediterranean diet was generally not associated with total mortality. Consumption of fruit and nuts (adjusted hazard ratio 0.82 [95% CI, 0.70 to 0.96]) and the ratio of monounsaturated fats to saturated fats (adjusted hazard ratio 0.86 [95% CI, 0.76 to 0.98]), however, were associated with reduced mortality.
Conclusion: Adherence to the Mediterranean diet is associated with a significant reduction in total mortality, CHD, and cancer mortality. Individual components of the diet are not generally predictive of total mortality, suggesting that multiple dietary components are necessary to yield the most protective effect.