Nov. 10, 2008 -- An eight-year study involving nearly 15,000 male physicians failed to show a benefit for vitamins C and E in preventing heart attacks or strokes.
The new study supports previous findings from other large trials showing no benefit for vitamin E. But it is one of the first large studies to examine the impact of vitamin C supplementation on cardiovascular risk.
"We saw no effect for either vitamin E or C in this study of men with a low initial risk for cardiovascular disease," researcher Howard D. Sesso, ScD, of Boston's Brigham and Women's Hospital, tells WebMD.
Just a decade ago, when enrollment for the Physicians' Health Study II was occurring, much excitement surrounded antioxidants like vitamin C, vitamin E, and beta-carotene.
But recent studies examining antioxidant supplementation in humans have largely been disappointing, showing little or no impact on cardiovascular risk.
The new study, published in the Nov. 12 issue of TheJournal of the American Medical Association, is one of the most rigorously designed trials to ever address the issue.
A total of 14,641 male physicians who were 50 or older at enrollment took either 500 milligrams of vitamin C and a placebo, 400 International Units (IU) of vitamin E and a placebo, both vitamins, or two placebos every other day for an average of eight years.
During this time there were 1,245 confirmed major cardiovascular events among the study participants.
Neither vitamin, nor the combination of the two, was found to have a significant impact on the risk for heart attack, stroke, or other cardiovascular events.
The researchers conclude that the findings provide no support for the use of these supplements for the prevention of cardiovascular disease in middle-aged and elderly men.
Studies in women have also shown little or no benefit for vitamin E supplementation.
"There haven't been as many well-designed large trials of vitamin C so one could argue that the jury may still be out," Sesso says.
Multivitamins and Heart Risk
Sesso and colleagues are continuing to follow men in their study who are taking a multivitamin supplement.
"This is the only trial that I am aware of examining multivitamin use over more than a decade of follow-up," he says.
"The prevalence of multivitamin use is very high. Many people, including myself, take them without really having any hard evidence from long-term, large-scale clinical trials to support claims of benefits."
Mayo Clinic cardiologist Raymond Gibbons, MD, says patients want to believe that vitamins can protect their hearts even though there is little evidence to support this.
Gibbons is a past president of the American Heart Association.
"When I tell my patients there is no data to support the use of vitamins they don't want to believe me," he says. "A lot of money has gone into promoting vitamins for heart health, and manufacturers can make very bold claims because vitamins aren't regulated by the FDA."
Annette Dickinson, PhD, past president of the supplement industry trade group Council for Responsible Nutrition, says in a news release that vitamins still have other important uses.
"These results do not of course negate other evidence of benefits for vitamin E and vitamin C for other conditions, including immune function, mental acuity, and eye health. Consumers would be well advised to ensure adequate intakes of all essential nutrients through a good diet plus use of a multivitamin, and selected other nutrients including vitamins E and C, vitamin D, calcium, and EPA and DHA omega-3 fatty acids."