High doses of Vitamin E, which millions of people take to protect themselves against heart attacks, Alzheimer's disease and other ailments, appear to actually increase the overall risk of dying, researchers reported yesterday.
A new analysis of data from 19 studies involving nearly 136,000 people concluded that the overall risk of dying began to increase at the dose in a typical single capsule of Vitamin E, and that the more Vitamin E people took, the more their risk of death rose. Someone taking 400 international units of Vitamin E a day for five years, for example, would face a 5 percent higher risk of dying, the researchers found.
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The study found no increased risk from lower doses, particularly at doses of 200 international units or below, and perhaps even a benefit. A typical multivitamin contains 30 to 60 international units of Vitamin E.
Although the study did not examine how high-dose Vitamin E might increase the risk of death, other studies have suggested that the substance may boost the danger of heart attacks and strokes, perhaps by affecting blood clotting or blocking the beneficial effects of other nutrients, the researchers said.
Whatever the mechanism, the findings indicate that no one should take high doses regularly and that current guidelines for what is considered a safe maximum daily intake should be lowered, the researchers said in a study presented at an American Heart Association meeting in New Orleans.
"A lot of people take vitamins because they believe it will benefit their health in the long term and prolong life," said Edgar R. Miller III, an associate professor of medicine at the Johns Hopkins University School of Medicine, who led the research. "But our study shows that use of high-dose Vitamin E supplements certainly did not prolong life but was associated with a higher risk of death."
The findings are the latest in a series of recent findings undermining the theory that "antioxidant" substances may provide powerful protection against a host of illnesses. Evidence had suggested that vitamins and other compounds found naturally in many foods might reduce the risk of heart disease, cancer and other illnesses by preventing unstable oxygen molecules known as free radicals from damaging DNA. That has prompted many Americans to take supplements containing high doses of antioxidants, including Vitamin E.
In 2003, Americans spent $710 million on Vitamin E, making it the second most popular individual vitamin, behind Vitamin C, according to the Nutrition Business Journal, which tracks industry trends.
But when researchers have attempted to give antioxidants to prevent disease, the results largely have been disappointing, and sometimes alarming. Beta carotene, for example, was found to increase rather than decrease the risk of lung cancer.
The latest study suggests that may be true for Vitamin E, as well, experts said.