Potassium, Calcium, and Magnesium Intakes and Risk of Stroke in Women

Susanna C. Larsson; Jarmo Virtamo; Alicja Wolk

Disclosures

Am J Epidemiol. 2011;174(1):35-43. 

In This Article

Abstract and Introduction

Abstract

The authors examined the association between dietary potassium, calcium, and magnesium intakes and the incidence of stroke among 34,670 women 49–83 years of age in the Swedish Mammography Cohort who completed a food frequency questionnaire in 1997. The authors used Cox proportional hazards regression models to estimate relative risks and 95% confidence intervals. During a mean follow-up of 10.4 years (1998–2008), 1,680 stroke events were ascertained, including 1,310 cerebral infarctions, 154 intracerebral hemorrhages, 79 subarachnoid hemorrhages, and 137 unspecified strokes. There was no overall association between potassium, calcium, or magnesium intake and the risk of any stroke or cerebral infarction. However, among women with a history of hypertension, potassium intake was inversely associated with risk of all types of stroke (for highest vs. lowest quintile, adjusted relative risk = 0.64, 95% confidence interval (CI): 0.45, 0.92) and cerebral infarction (corresponding adjusted relative risk = 0.56, 95% CI: 0.38, 0.84), and magnesium intake was inversely associated with risk of cerebral infarction (corresponding adjusted relative risk = 0.63, 95% CI: 0.42, 0.93). Calcium intake was positively associated with risk of intracerebral hemorrhage (for highest vs. lowest tertile, adjusted relative risk = 2.04, 95% CI: 1.24, 3.35). These findings suggest that potassium and magnesium intakes are inversely associated with the risk of cerebral infarction among hypertensive women.

Introduction

Stroke is a leading cause of morbidity and mortality in industrialized countries.[1] Dietary factors may influence the risk of stroke through several mechanisms—for example, by effects on blood pressure, insulin resistance, systemic inflammation, platelet function, thrombosis, and oxidation.[2] Dietary intakes of potassium, calcium, and magnesium have been inversely associated with blood pressure and hypertension in several observational studies.[3–7] In addition, some, but not all, randomized controlled trials have shown that supplementation with potassium, calcium, and magnesium alone or in combination reduced blood pressure.[8–11] Magnesium intake has also been inversely associated with markers of systemic inflammation,[12] endothelial dysfunction,[12] carotid artery thickness,[7] fasting insulin concentrations,[7] the metabolic syndrome,[13] and type 2 diabetes mellitus (hereafter referred to as diabetes).[14] Findings from prospective studies of intakes of potassium,[15–22] calcium,[16,17,22–25] and/or magnesium[16,17,22,26,27] in relation to stroke incidence or mortality have been inconsistent. The relations of potassium, calcium, and magnesium intakes with the incidence of stroke could be modified by hypertension.[16,18] However, only a few studies[16,18,22] have examined the potential modifying effect of hypertension on the association between potassium, calcium, and magnesium intakes and the risk of stroke.

We analyzed data from the Swedish Mammography Cohort, a population-based prospective cohort study of women, to assess the hypothesis that high intakes of potassium, calcium, and magnesium are associated with a reduced incidence of stroke. We examined whether the associations between intake of these minerals and risk of stroke were modified by a history of hypertension. To our knowledge, this is the largest prospective study (with regard to number of cases) to date that assessed the relation between potassium, calcium, and magnesium intakes and the risk of stroke in women.

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