Do antioxidant supplements increase mortality?
Last Updated Aug 2007
A recent article in the Journal of the American Medical Association came to the
conclusion that mortality is increased in subjects consuming high doses of
antioxidant supplements. Talk about making the vitamin and supplement industry
mad. Who is right? As usual, you have to follow the science that often gets
confusing in these meta-analysis trials.
First, the conclusions were only germane to synthetic vitamins, such as Vitamin E,
Vitamin A, and beta-carotene. Vitamin C was shown to have no effect either way,
and selenium was slightly protective against mortality. Second, any study that
didn't have any reported deaths was automatically excluded from the meta analysis.
This means only those studies in which the subjects were already quite ill were
analyzed. Third, conclusions are only relative to mega doses of these
supplements.
How might megadoses of antioxidant supplements be harmful? It is only the fat-
soluble supplements that were suspect. These are the ones that also inhibit the
formation of any eicosanoid (good or bad) since free radicals are important in the
synthesis of these hormones. At low levels, excess free radical production would
be inhibited (that's good), but at high levels the formation of good eicosanoids
would be inhibited (that's bad). You would get the same effect if you took high
doses of corticosteroids. In a sick population, that is probably a good way to
accelerate death.
Bottom line: Take a reasonable level of fat-soluble antioxidants to keep them in a
zone that is not too high, but not too low. What is a good upper limit? No more
than 5,000 IU of Vitamin A and no more than 400 IU of Vitamin E per day. A good
multi-vitamin is a cheap insurance policy. Before you take antioxidants, consider
the benefits of polyphenols, powerful chemical substances that give fruits and
vegetables their color. Not surprisingly, fruits and vegetables are the two
carbohydrate mainstays of the Zone Diet.