Intakes of magnesium, potassium, and calcium and the risk of stroke among men

Background Intakes of magnesium, potassium, and calcium have been inversely associated with the incidence of hypertension, a known risk factor for stroke. However, only a few studies have examined intakes of these cations in relation to risk of stroke. Aim The aim of this study was to investigate whether high intake of magnesium, potassium, and calcium is associated with reduced stroke risk among men. Methods We prospectively examined the associations between intakes of magnesium, potassium, and calcium from diet and supplements, and the risk of incident stroke among 42 669 men in the Health Professionals Follow-up Study, aged 40 to 75 years and free of diagnosed cardiovascular disease and cancer at baseline in 1986. We calculated the hazard ratio of total, ischemic, and haemorrhagic strokes by quintiles of each cation intake, and of a combined dietary score of all three cations, using multivariate Cox proportional hazard models. Results During 24 years of follow-up, 1547 total stroke events were documented. In multivariate analyses, the relative risks and 95% confidence intervals of total stroke for men in the highest vs. lowest quintile were 0.87 (95% confidence interval, 0.74-1.02; P, trend = 0.04) for dietary magnesium, 0.89 (95% confidence interval, 0.76-1.05; P, trend = 0.10) for dietary potassium, and 0.89 (95% confidence interval, 0.75-1.04; P, trend = 0.25) for dietary calcium intake. The relative risk of total stroke for men in the highest vs. lowest quintile was 0.74 (95% confidence interval, 0.59-0.93; P, trend = 0.003) for supplemental magnesium, 0.66 (95% confidence interval, 0.50-0.86; P, trend = 0.002) for supplemental potassium, and 1.01 (95% confidence interval, 0.84-1.20; P, trend = 0.83) for supplemental calcium intake. For total intake (dietary and supplemental), the relative risk of total stroke for men in the highest vs. lowest quintile was 0.83 (95% confidence interval, 0.70-0.99; P, trend = 0.04) for magnesium, 0.88 (95% confidence interval, 0.75-4; P, trend = 6) for potassium, and 3 (95% confidence interval, 79-09; P, trend = 84) for calcium. Men in the highest quintile for a combined dietary score of all three cations had a multivariate relative risk of 0.79 (95% confidence interval, 0.67-0.92; P, trend = 0.008) for total stroke, compared with those in the lowest. Conclusions A diet rich in magnesium, potassium, and calcium may contribute to reduced risk of stroke among men. Because of significant collinearity, the independent contribution of each cation is difficult to define.