A large, randomized trial suggests that taking daily
vitamin E supplements may increase a manís risk of
ďI counsel all of my patients to absolutely avoid
any dietary supplements that contain selenium or
vitamin Eóincluding multivitaminsĒ says prostate
cancer expert Dr. Marc Garnick, a clinical professor
of medicine at Harvard Medical School, an oncologist
at Beth Israel Deaconess Medical Center, and editor
in chief of Harvardís Annual Report on Prostate
Studies done in the 1980s and 1990s suggested that
vitamin E and selenium each somehow provided
protection against prostate cancer.
The Selenium and Vitamin E Cancer Prevention Trial
(SELECT) was started in 2001 to see if that was
The 36,000 healthy, middle-aged volunteers were
divided into four groups.
Each man took two pills a day: 400 international
units (IU) of vitamin E plus 200 micrograms of
selenium; vitamin E plus a placebo; selenium plus a
placebo; or two placebos.
Neither the men nor their doctors knew who was
Although SELECT was supposed to last until 2011, it
was stopped three years early because neither
vitamin E nor selenium were showing any benefitóand
there were hazy warning signs they might be doing
A new report in the Journal of the National Cancer
Institute clarifies the picture.
A team of researchers from across the U.S. looked
specifically at almost 5,000 of the SELECT
volunteers who sent in toenail clippings when they
joined the trial.
Toenail clippings are a great way to measure how
much selenium is in a manís (or womanís) body.
The new study showed that:
Taking vitamin E alone boosted the risk of
developing high-grade prostate cancer, but only in
men who started the study with low selenium levels.
Taking selenium, either alone or in combination with
vitamin E, increased the risk of high-grade prostate
cancer in men who started the study with high
selenium levels, but not in those with low selenium
Among men who didnít take either vitamin E or
selenium, those who started the study with high
selenium levels were no more likely to have
developed prostate cancer than men who started it
with low selenium levels.
This means the culprit is added selenium from
supplements, not selenium from food.
Men should avoid selenium or vitamin E
supplementation at doses that exceed recommended
For more information
Baseline Selenium Status and Effects of Selenium and
Vitamin E Supplementation on Prostate Cancer Risk
The Journal of the National Cancer Institute
Harvard Medical School