Sept. 10, 2007 -- Vitamin E proved to be a bust for preventing heart disease and cancer in a widely publicized study in women, but intriguing results from the same trial suggest a role for the vitamin in reducing the risk of life-threatening blood clots.
Researchers warn that the findings must be confirmed, and they say no one taking prescription blood thinners to prevent deep vein blood clots should stop taking them.
But Harvard Medical School professor of medicine Robert J. Glynn, PhD, says vitamin E shows promise for preventing the potentially deadly clots in high-risk patients who aren't on prescription blood thinners like warfarin.
"Warfarin is very effective, but it has a lot of side effects and people must be monitored closely when they are on it," Glynn tells WebMD.
Vitamin E and Deep Vein Clots
Clots that form in the arteries lead to heart attacks and strokes, but deep vein clots become deadly when they break off and travel to the lungs, causing pulmonary embolisms. Deep vein clots and pulmonary embolism from blood clots are known collectively as venous thromboembolism (VTE).
That is what happened to NBC reporter David Bloom, who died in 2003 after spending days in a cramped military vehicle while covering the invasion of Iraq.
Spending long periods in a confined space without moving greatly increases a person's risk for developing deep vein blood clots, as do obesity, pregnancy, advanced age, oral contraceptives, and hormone therapy.
The American Heart Association (AHA) estimates that about 200,000 new cases of VTE occur in the U.S. each year, with 30% of cases resulting in death within 30 days. Another 30% of people develop new clots within 10 years.
In the newly published study, Glynn and colleagues reviewed data from the Women's Health Study, which included just under 40,000 women aged 45 and older who took either 600 international units (IU) of vitamin E or a placebo every other day and were followed for an average of 10 years.
During the trial, 213 women in the vitamin E group and 269 women in the placebo group developed venous thromboembolism.
Overall, women who took vitamin E were 21% less likely to develop venous thromboembolism than women who did not, but the reduction was more than double this (44%) among the women who had a history of clots.
And taking vitamin E appeared to cut the clot risk in half among women with genetic mutations that increased their risk.
The study appears in the Sept. 25 issue of the AHA journal Circulation.
"The puzzle fits together in a way that is really interesting, suggesting a possible benefit in precisely the people who need it most," Glynn says.
Vitamin E 'Not Ready for Prime Time'
The American Heart Association does not recommend antioxidant vitamins like vitamin E, C, and beta-carotene for preventing heart attacks and strokes, and a 2004 analysis of 14 studies suggested that taking 400 IU of vitamin E a day or more increased the risk of death.
But Glynn says no significant side effects were seen among women in the study who took vitamin E for an average of 10 years.
He says more study is needed to confirm the findings, and New York University cardiologist Nieca Goldberg, MD, agrees.
Goldberg directs NYU's women's heart program and is a spokeswoman for the AHA.
"This is very interesting, but it isn't necessarily ready for prime time," she tells WebMD. "People on strong blood thinners like warfarin should absolutely stay on them, and anyone else who might consider taking vitamin E for this reason should discuss it with their doctor first."