Dairy foods and risk of stroke: a meta-analysis of prospective cohort studies

Background and aims: Epidemiological studies evaluating the association of dairy foods with risk of stroke have produced inconsistent results. We conducted a meta-analysis to summarize the evidence from prospective cohort studies regarding the association between dairy foods and risk of stroke.

Methods and results: Pertinent studies were identified by searching Embase (1950-November, 2013), Web of Knowledge (1950-November, 2013) and Pubmed (1945-November, 2013). Random-effect model was used to combine the results. Dose-response relationship was assessed by restricted cubic spline. Eighteen separate results from fifteen prospective cohort studies, with 28,138 stroke events among 764,635 participants, were included. Total dairy [relative risk (95% CI): 0.88 (0.82-0.94)], low-fat dairy [0.91 (0.85-0.97)], fermented milk [0.80 (0.71-0.89)] and cheese [0.94 (0.89-0.995)] were significantly associated with reduced risk of stroke, but whole/high-fat dairy, nonfermented milk, butter and cream were not significantly associated with risk of stroke. Stronger association was found for stroke mortality than incidence, and for studies conducted in Asia than Europe, while the association did not differ significantly by sex. Limited data did not find any significant association with either ischemic or hemorrhagic stroke. A non-linear dose-response relationship (P = 2.80*10(-13)) between milk and risk of stroke was found, and the relative risk of stroke was 0.88 (0.86-0.91), 0.82 (0.79-0.86), 0.83 (0.79-0.86), 0.85 (0.81-0.89), 0.86 (0.82-0.91), 0.91 (0.84-0.98) and 0.94 (0.86-1.02) for 100, 200, 300, 400, 500, 600 and 700 ml/day of milk, respectively.

Conclusions: Dairy foods might be inversely associated with the risk of stroke.