MedWire News: Vitamin E supplements significantly reduce the risk of venous thromboembolism (VTE) by up to almost 50%, results from the Women's Health Study (WHS) demonstrate.

"Given its lack of efficacy for prevention of cardiovascular disease and cancer, vitamin E may be most appropriate for people at high risk of VTE," Robert Glynn (Brigham and Women's Hospital, Boston, Massachusetts, USA) and team say.

As vitamin E is thought to inhibit vitamin K and vitamin K-dependent clotting factors, the researchers examined WHS findings to determine whether the vitamin alters the risk for VTE.

In all, 39,876 women aged 45 years and older were randomly assigned to take vitamin E 600 IU on alternate days or placebo. Blood samples for 26,779 women were tested for known prothrombotic mutations.

Over a median of 10.2 years of follow-up, 482 women developed VTE. A total of 213 episodes occurred in those given vitamin E and 269 in patients given placebo. Vitamin E reduced the risk for VTE by a significant 21% (hazard ratio=0.79).

For women with no history of VTE, vitamin E supplements reduced the risk for VTE by a significant 18%. For women with a previous history of VTE, the risk fell by 44% among those taking vitamin E, reducing the estimated 10-year rate of events from 5.5% with placebo to 3.2%.

Data for 3097 women at high-risk for VTE, due to history of events or a factor V Leiden or prothrombin G20210A mutation, showed that vitamin E supplements reduced the risk for VTE by 49%. The estimated 10-year rate of events decreased from 4.1% with placebo to 2.1% with vitamin E.

Writing in the journal Circulation, Glynn et al conclude: "These data suggest that supplementation with vitamin E may reduce the risk of VTE in women, and those with a prior history or genetic predisposition may particularly benefit."

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