The Washington Post

Is that right? Vitamin C lowers blood pressure?

People have placed lots of stock in vitamin C to address all kinds of health issues; many people swear by it as a way to ward off the common cold, for instance, even though that connection is scientifically shaky.

The idea that vitamin C might help lower blood pressure got a bit of a boost with the publication on Monday of a study showing a modest reduction in blood pressure readings associated with consumption of vitamin C supplements.

The catch? People in the study, which was published in the American Journal of Clinical Nutrition, had to take about 500 milligrams of vitamin C a day to see their blood pressure drop. That’s more than five times the 75 to 90 milligrams currently recommended for most adults.

Researchers at the Johns Hopkins University School of Medicine reviewed data from 29 published accounts of randomized, controlled clinical trials involving blood pressure; they included only those in which vitamin C intake was compared to placebo controls. The median length of the studies was eight weeks.

Overall, they found that taking those 500 mg of vitamin C was associated with a nearly 4-millimeter drop in mercury in systolic blood pressure measures; among people with hypertension, there was a nearly 5-millimeter-of-mercury drop.

That sounds promising, though the study’s lead author, Edgar “Pete” Miller, associate professor of general internal medicine at Johns Hopkins, points out that people who take ACE inhibitors or diuretics to control their blood pressure typically see a 10-millimeter drop in the mercury reading.

The study cautions against taking big doses of vitamin C as a blood-pressure regulator, at least until more research — including studies that last longer than a few weeks, as those in this paper did, and with larger numbers of participants — is done. Still, vitamin C is an important nutrient, and because our bodies don’t store it, it’s not something you have to worry about overdosing on.

And nobody would object to your adding more vitamin C-rich foods to your diet. My favorite such food is red bell pepper, which contains nearly 300 mg of vitamin C per cup. What’s yours?


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