Heart Health Hampered by Vitamin C Supplements, Study Shows
WebMD News Archive
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
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
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
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
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.