Mediterranean diet and mortality in Switzerland: an alpine paradox?

Reports on the protective effect of a Mediterranean diet on mortality usually refer to populations from Mediterranean countries, leaving uncertain whether really diet is the fundamental cause. Our aim was to examine the effect of a Mediterranean diet on mortality in Switzerland, a country combining cultural influences from Mediterranean and Central European countries within a common national health and statistical registry.

In this prospective investigation, we included 17,861 men and women aged ≥16 years who participated 1977-1993 in health studies and were followed up for survival until 2008 by anonymous record linkage with the Swiss National Cohort. A 9-point score Mediterranean Diet Score (MDS) was used to assess adherence to a Mediterranean diet. Mortality hazard ratios (HR) and 95% confidence intervals (CIs) were calculated by using Cox regression models adjusted for age, sex, survey wave, marital status, smoking, body mass index, language region and nationality.

In all language regions, MDS was inversely associated with mortality. Consumption of dairy products was also consistently associated with lower mortality. When categorizing dairy food consumption as beneficial instead of harmful, this association between MDS and mortality increased in strength and was partly statistically significant. For all causes of death combined (HR for a one-point increase in MDS 0.96, 95% CI 0.94-0.98), in men (0.94, 0.92-0.97), in women (0.98, 0.95-1.02) for cardiovascular diseases (CVD, 0.96, 0.92-0.99; 0.95, 0.90-1.00; 0.98, 0.92-1.04) and for cancer (0.95, 0.92-0.99; 0.92, 0.88-0.97; 0.98, 0.93-1.04).

Stronger adherence to a Mediterranean diet was associated with lower all-cause, CVD and cancer mortality, largely independently of cultural background. These associations were primary due to the effect in men. Our finding of a beneficial rather than a deleterious impact of dairy products consumption prompts at considering culturally adapted Mediterranean diet recommendations. However, results should be interpreted with caution since only a crude 1-day dietary estimate was available to assess individuals' habitual dietary intake.