Calcium Intake and the Risk of Stroke: An Up-dated Meta-analysis of Prospective Studies

Background and Purpose: Calcium intake has been associated with stroke risk in a prior meta-analysis, however, newly published results are inconsistent. Dairy food benefits on stroke incidence may involve a calciumrelated mechanism. We have therefore updated this meta-analysis with particular references to any possibility of a calcium-mediated dairy food risk reduction of stroke risk. Methods: We searched multiple databases and bibliographies for prospective cohort studies. Reports with multivariate-adjusted relative risk (RR) and corresponding 95% confidence intervals (CI) for the association of calcium intake with stroke incidence were considered. Results: Ten studies with 371,495 participants and 10,408 stroke events were analyzed. The pooled analysis showed no statistically significant association of the risk of total stroke (RR=0.96; 95% CI: 0.89-1.04) and stroke subtypes with the highest and lowest calcium intake quantiles. Nevertheless, high dairy calcium intake was significantly associated with an approximately 24% reduction of stroke risk. (RR=0.76; 95% CI: 0.66-0.86). Furthermore, a long-term follow-up (≥14 years) was helpful to reduce the risk of stroke (RR=0.67; 95% CI: 0.51-0.88). Additionally, a non-linear dose-response relationship was predicted between calcium intake and stroke risk. Conclusions: Dairy calcium intake is inversely associated with stroke incidence. There is a non-linear dose-response relationship between calcium intake and stroke risk. However, when the follow-up time is long enough, the inverse relationship is independent of dose. Additional large cohort studies are required to illustrate this relationship in detail.