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Heart Disease Health Center

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Heart Health Hampered by Vitamin C Supplements, Study Shows

WebMD Health News

March 2, 2000 (San Diego) -- Vitamin C supplements, long touted for their health benefits, may actually do more harm than good, says a Los Angeles researcher who tracked changes in the blood vessels that supply blood to the brain.

James H. Dwyer, PhD, of the University of Southern California (USC), found that men who took 500 mg of vitamin C had a rapid increase in thickening of the artery wall, which increases the risk of having a heart attack or stroke. Dwyer presented his findings at an American Heart Association meeting here Thursday.

Dwyer, who is a professor of preventive medicine at Keck School of Medicine at USC, used an ultrasound to measure the thickness of the carotid artery, which supplies blood to the brain. This is known to be an indicator of the amount of blockage in all the blood vessels in the body, including the heart. He collected measurements from more than 570 healthy men and then measured again 18 months later. The average age of the men was 54.

A daily dose of 500 mg of vitamin C was associated with a thickening rate that was 2.5 times greater than the rate in men who didn't use supplements, Dwyer tells WebMD. At a press conference, he said the effect was most striking among smokers. "The increase among smokers was fivefold," says Dwyer. And he says that even men whose arteries showed no evidence of disease at the outset had evidence of thickening after 18 months if they were taking vitamin C.

He says the data should be "treated as suggestive only because this is just one study, and there may be [other] variables that we have not uncovered."

Thomas A. Pearson, MD, MPH, PhD, of the University of Rochester in New York, says the findings are somewhat surprising. He tells WebMD that in a study presented last fall at the AHA annual meeting, a team of researchers from Finland reported that a combination of vitamin E and vitamin C appeared to prevent carotid thickening. It does point to the need for a more detailed study of vitamin C supplementation, Pearson says.

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