Up with potassium, down with blood pressure

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THE ROLE OF POTASSIUM in controlling blood pressure has been controversial because many of the studies designed to look for a possible connection have been too small or too poorly controlled to yield dependable findings. But after pooling the results of more than 30 well-conducted trials on potassium and blood pressure published since the 1920s, scientists at Johns Hopkins University and the National Heart, Lung, and Blood Institute concluded that people who have high blood pressure can lower it by increasing their potassium intakes. Moreover, high potassium consumption may keep hypertension from developing in the first place.

Consider the researchers' finding that in subjects with normal blood pressure, the average drop was 2 millimeters in systolic pressure (the first number in a reading) and 1 millimeter in diastolic pressure (the second number). That may not sound like much,but such reductions can decrease the risk of developing high blood pressure by some 25 percent, according to Jeffrey Cutler, MD, MPH, a blood pressure expert who worked on the project.

Study leader Paul Whelton, MD, MSc, noted that extra potassium appears to be especially beneficial to African-Americans, a group prone to high blood pressure. It also seems to be particularly helpful to people who are having trouble reducing their intake of sodium -- potassium's counterpart in blood pressure regulation.

Most of the people in the 30-plus trials analyzed by the researchers were given extra potassium in the form of potassium chloride supplements, but several studies involved potassium-rich foods. Drs. Cutler and Whelton say that people trying to lower their blood pressure will get the biggest nutrition bang for their buck with the dietary approach because the foods richest in potassium, namely fruits and vegetables, are also low in sodium, practically fat-free, and rich in fiber and other nutrients (see chart).

Those who might want to opt for potassium supplements despite foods' other benefits should talk with their doctors first. Potassium supplements can be dangerous to people with impaired kidney function as well as to those taking blood pressure-lowering drugs that fall into a class known as ACE inhibitors.

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