Older individuals who do not eat enough potassium-rich foods may be more susceptible to stroke, preliminary study findings suggest. The study of more than 5,600 men and women over 65 years of age found that those with the lowest dietary intake of potassium, a mineral found in bananas, tomato sauce, dried apricots and orange juice, were 1.5 times more likely to have a stroke over the next 4 to 8 years than their peers with higher intakes of potassium.
The investigators measured levels of potassium in the blood of healthy individuals who had never suffered a stroke, and recorded dietary potassium intake. High potassium intake was defined as more than 4 grams a day and low potassium intake was defined as less than 2.4 grams a day, roughly the amount in 1 cup of tomato sauce. The average dietary intake of potassium was 3.3 grams at the outset and the average age of study volunteers was nearly 73 years.
Among individuals taking diuretics, the risk of stroke was 2.5 times higher when blood levels of potassium were low. The risk of stroke was 10 times higher among diuretic users with an irregular heart rhythm known as atrial fibrillation and low potassium intake, compared with those with a normal heart rhythm and high intake of potassium, the researchers report.
Atrial fibrillation has long been known to increase the risk of stroke. Diuretics, or "water pills," lower blood pressure and reduce stroke risk but can also lower levels of potassium in the blood. Therefore, they may be more effective when dietary potassium intake is high.
However, the study does not imply that using diuretics raises the risk of stroke, the authors emphasize. Rather, it indicates that the pills may play a role among some patients, including those with diabetes and high blood pressure.
Experts emphasize that this study is observational and does not prove the low potassium level is the cause for the higher stroke risk. It is possible that some unknown factor may reduce potassium level and raise stroke risk. Nor do the findings support any recommendations regarding dietary potassium intake. Their advice for patients is to eat a balanced diet that includes plenty of fruits and vegetables.
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