Dietary Sodium to Potassium Ratio and Risk of Stroke in a Multiethnic Urban Population: The Northern Manhattan Study

Abstract

Background and purpose: There is growing evidence that increased dietary sodium (Na) intake increases the risk of vascular diseases, including stroke, at least in part via an increase in blood pressure. Higher dietary potassium (K), seen with increased intake of fruits and vegetables, is associated with lower blood pressure. The goal of this study was to determine the association of a dietary Na:K with risk of stroke in a multiethnic urban population.

Methods: Stroke-free participants from the Northern Manhattan Study, a population-based cohort study of stroke incidence, were followed-up for incident stroke. Baseline food frequency questionnaires were analyzed for Na and K intake. We estimated the hazard ratios and 95% confidence intervals for the association of Na:K with incident total stroke using multivariable Cox proportional hazards models.

Results: Among 2570 participants with dietary data (mean age, 69±10 years; 64% women; 21% white; 55% Hispanic; 24% black), the mean Na:K ratio was 1.22±0.43. Over a mean follow-up of 12 years, there were 274 strokes. In adjusted models, a higher Na:K ratio was associated with increased risk for stroke (hazard ratio, 1.6; 95% confidence interval, 1.2-2.1) and specifically ischemic stroke (hazard ratio, 1.6; 95% confidence interval, 1.2-2.1).

Conclusions: Na:K intake is an independent predictor of stroke risk. Further studies are required to understand the joint effect of Na and K intake on risk of cardiovascular disease.

Keywords: diet; epidemiology; potassium; sodium; stroke.