Mega Multivitamins and Prostate Cancer
Higher Doses Linked to Higher Death Risk
WebMD News Archive
May 15, 2007 -- Men who take too many multivitamins may be increasing their
risk of dying from prostate cancer, according to new research from the National
Taking a multivitamin more than seven times a week was associated with a 30%
increased risk of advanced prostate cancer and a doubling of the risk of death
from the disease in the study.
Regular multivitamin use (one to six times a week) did not appear to
increase cancer risk, and excessive vitamin use was not associated with an
increased risk of early, or localized, prostate cancer.
But there was also no evidence to suggest that taking multivitamins at any
dosage helped prevent prostate cancer.
NCI researcher Michael F. Leitzmann, MD, PhD, tells WebMD that more research
is needed to confirm the association and understand how vitamin and other
dietary supplements affect cancer risk.
“Based on our findings, we would recommend that men adhere to
recommendations for dietary supplements and consult with their physician before
taking supplements in excessive doses,” he says.
More Questions About Safety
The new research is one of several recent studies suggesting a potential
downside to vitamin supplementation in people who are generally
An analysis of 47 studies assessing antioxidant supplementation, published
earlier this year, found a slight increase in deaths among people who took
beta-carotene, vitamin E, or vitamin A supplements.
Christian Gluud, MD, who co-authored the analysis, tells WebMD that there is
little evidence of a benefit for antioxidant supplementation and mounting
evidence of potential harm.
“The idea that you can prevent disease by taking an antioxidant supplement
is very attractive,” he says. “People want to believe it, and there is a great
deal of marketing devoted to making them believe it.”
In the latest study, Leitzmann, co-author Karla Lawson, PhD, and NCI
colleagues followed slightly more than 295,000 men enrolled in a diet and
health study for five years.
During this time, 8,765 men in the study were diagnosed with localized
prostate cancer (cancer that hasn't spread beyond the prostate) and 1,476 with
advanced prostate cancer (cancer that has spread beyond the prostate).