Hypertension is the most important known risk factor for stroke. Clinical, experimental,
and epidemiologic evidence suggests that a high dietary intake of potassium is associated
with lower blood pressure. In hypertensive rats, a high intake of potassium is reported
to protect against stroke, even though blood pressure is not affected. We examined
the relation between the 24-hour dietary potassium intake at base line and subsequent
stroke-associated mortality in a population-based cohort of 859 men and women (aged
50 to 79 years) in Southern California. After 12 years, 24 stroke-associated deaths
had occurred. The relative risks of stroke-associated mortality in the lowest tertile
of potassium intake, as compared with that in the top two tertiles combined, were
2.6 (P = 0.16) in men and 4.8 (P = 0.01) in women. In multivariate analyses, a 10-mmol
increase in daily potassium intake was associated with a 40 percent reduction in the
risk of stroke-associated mortality (P less than 0.001). This effect was independent
of other dietary variables, including the intake of calories, fat, protein, fiber,
calcium, magnesium, and alcohol. The effect was also apparently independent of known
cardiovascular risk factors, including age, sex, blood pressure, blood cholesterol
level, obesity, fasting blood glucose level, and cigarette smoking. These findings
support the hypothesis that a high intake of potassium from food sources may protect
against stroke-associated death.