— America's favorite dietary supplements, multivitamins, modestly lowered the risk for cancer in healthy male doctors who took them for more than a decade, the first large study to test these pills has found.
The result is a surprise because many studies of individual vitamins have found they don't help prevent chronic diseases and some have even caused problems.
In the new study, multivitamins cut the chance of developing cancer by 8 percent. That is less effective than a good diet, exercise and not smoking, each of which can lower cancer risk by 20 percent to 30 percent, cancer experts say.
Multivitamins also may have different results in women, younger men or people less healthy than those in this study.
"It's a very mild effect and personally I'm not sure it's significant enough to recommend to anyone" although it is promising, said Dr. Ernest Hawk, vice president of cancer prevention at the University of Texas MD Anderson Cancer Center and formerly of the National Cancer Institute.
"At least this doesn't suggest a harm" as some previous studies on single vitamins have, he said.
Hawk reviewed the study for the American Association for Cancer Research, which is meeting in Anaheim, Calif., where the study was to be presented on Wednesday. It also was published online in the Journal of the American Medical Association.
About one-third of U.S. adults and as many as half of those over 50 take them. They are marketed as a kind of insurance policy against bad eating. Yet no government agency recommends their routine use "regardless of the quality of a person's diet," says a fact sheet from the federal Office of Dietary Supplements.
Some fads, such as the antioxidant craze over vitamins A and E and beta-carotene, backfired when studies found more health risk with those supplements, not less. Many of those were single vitamins in larger doses than the "100 percent of daily value" amounts that multivitamins typically contain.