Vitamins: Separating Fact From Fiction
Experts cut through the hype about the health benefits of vitamin supplements.
There is promising evidence that the mineral selenium could prevent a
variety of cancers, says Alan Kristal, DrPh, associate chief of cancer
prevention at the Fred Hutchinson Cancer Research Center in Seattle. But beyond
selenium, the data aren't promising, Kristal says. For example, there's no
solid evidence that taking large doses of antioxidants like vitamins B or C
have any beneficial effect.
Controversial Health Claims
As you seek the proper multivitamin or dietary supplement, it's best to keep
your guard up. The supplement industry is relatively unregulated, and you can
injure or even kill yourself with "natural" products bought at your
neighborhood supplement store.
Many health claims attached to multivitamin formulations are doubtful, but
harmless. Some men's multivitamins contain extra lycopene, a substance once
thought to prevent prostate cancer. But Kristal, the cancer specialist, says
support for that claim is waning. "If indeed lycopene did anything,
[supplements] don't have enough to make a difference," he says.
Multivitamins aimed at women are often spiked with green tea or ginseng
extract; the effect of these on weight control is yet unproven.
More dangerous are recommendations of vitamin megadoses to treat obesity,
depression, carpal tunnel syndrome or other problems. At best, megadoses are a
distraction from real treatments for these problems, experts say. At worst,
they can cause injury or death.
So-called fat-soluble vitamins -- that is, vitamins A, D, E, and K --
accumulate in the body, making overdosing a real threat. Vitamin overdoses have
been associated with liver problems, weakened bones, cancers, and premature
Until recently, water-soluble vitamins such as B and C were considered
nontoxic, even at high doses. But now evidence is emerging that B-6 megadoses
can cause serious nerve damage, Bailey tells WebMD.
Despite the warnings, the quest for a magic pill plunges ahead. Cross
chuckles when patients show her weight loss supplements that claim wondrous
effects "when taken in combination with a sensible diet and exercise."
Her response: Wouldn't a sensible diet and exercise do the trick even without