Potassium-rich diet tied to lower stroke risk

NEW YORK Wed Aug 17, 2011 1:50pm EDT

A customer looks bananas in a supermarket in Sydney April 27, 2011. REUTERS/Daniel Munoz

A customer looks bananas in a supermarket in Sydney April 27, 2011.

Credit: Reuters/Daniel Munoz

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NEW YORK (Reuters Health) - People who eat plenty of high-potassium fruits, vegetables and dairy products may be less likely to suffer a stroke than those who get little of the mineral, a new study suggests.

The findings, reported in the journal Stroke, come from an analysis of 10 international studies involving more than 200,000 middle-aged and older adults.

Researchers found that across those studies, stroke risk dipped as people's reported potassium intake went up. For each 1,000-milligram (mg) increase in daily potassium, the odds of suffering a stroke in the next five to 14 years declined by 11 percent.

That would translate into a modest benefit for any one person, the researchers say. And the findings do not prove that potassium, itself, is what produces the positive effect.

But they strengthen existing evidence that it might, said lead researcher Susanna C. Larsson, of the Karolinska Institute in Stockholm, Sweden.

Since high-potassium foods are generally healthy ones -- including beans, a variety of fruits and vegetables, and low-fat dairy -- the findings offer one more reason for people to eat more of them, Larsson told Reuters Health in an email.

Potassium is an electrolyte needed for maintaining the body's fluid balance. It's also involved in nerve and muscle control and blood pressure regulation. A number of studies have suggested that diets high in potassium help maintain a healthy blood pressure and possibly protect against heart disease and stroke.

Of the nearly 270,000 participants Larsson and her colleagues included in their study, 8,695 (about one in 30) suffered a stroke. But the drop in stroke risk seen with every 1,000 mg increase in daily potassium was with factors like age, exercise habits and smoking taken into account.

Potassium was specifically linked to reduced risk of ischemic strokes -- those caused by a blockage in an artery feeding the brain. They account for about 80 percent of strokes.

The mineral was not, however, linked to a lower risk of hemorrhagic stroke, which occurs when there is bleeding in the brain.

It's not clear why that is, according to Larsson, who noted that only a few of the studies actually broke strokes down into subtypes.

If potassium protects against ischemic stroke only, that would suggest there are reasons other than better blood pressure control, the researchers say.

The findings are in line with a recent study by the U.S. Centers for Disease Control and Prevention (CDC) that followed more than 12,000 adults for 15 years.

Researchers found that people who downed a lot of sodium but little potassium were more likely to die from any cause during the study period.

Potassium helps balance the effects of sodium, keeping blood pressure down and helping the body excrete excess fluids. So the combination of too much sodium and too little potassium may be especially harmful.

But experts say that imbalance is common in the U.S. diet, with about 90 percent of Americans getting more sodium than is recommended -- often from processed foods.

According to the CDC, the average adult should get no more than 2,300 mg of sodium per day. Certain people -- adults older than 50, African Americans, and people with high blood pressure, diabetes or kidney disease -- should limit sodium to 1,500 mg a day.

As for potassium, the CDC advises adults to get 4,700 mg a day from food.

There are some people, though, who need to be careful about potassium. They include people with kidney disease, which can hinder the body's ability to clear potassium, and those on certain blood pressure drugs.

Too much potassium in the blood can lead to a condition called hyperkalemia, which may cause dangerous heart-rhythm disturbances.

SOURCE: bit.ly/pp9xgv Stroke, online July 28, 2011.

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