Editor's note: Does the study mean vitamins are useless? No. Vitamins are always vitamins. Try to use a nutrition-balanced diet and if neccessary take vitamin supplements.
Contact: Caroline McNeil
Journal of the National Cancer Institute
Vitamins C and E and beta carotene again fail to reduce cancer risk in randomized controlled trial
Women who took beta carotene or
vitamin C or E or a combination of the supplements had a similar risk
of cancer as women who did not take the supplements, according to data
from a randomized controlled trial in the December 30 online issue of
Journal of the National Cancer Institute.
studies have suggested that people whose diets are high in fruits and
vegetables, and thus antioxidants, may have a lower risk of cancer.
Results from randomized trials that address the issue, however, have
been inconsistent and have rarely supported that observation.
the current study, Jennifer Lin, Ph.D., of the Brigham and Women's
Hospital and Harvard Medical School in Boston, and colleagues tested
the impact of antioxidant supplements on cancer incidence in a
randomized controlled trial. A total of 7,627 women who were at high
risk of cardiovascular disease were randomly assigned to take vitamin
C, vitamin E, or beta-carotene.
With an average of 9.4 years
of follow-up time, there was no statistically significant benefit from
antioxidant use compared with placebo in terms of disease risk or
mortality due to cancer. Overall, 624 women developed cancer and 176
died from cancer during the follow-up time. Compared with placebo, the
relative risk of a new cancer diagnosis was 1.11 for women who took
vitamin C, 0.93 for women who took vitamin E, and 1.00 for women who
took beta carotene. None of these relative risks was statistically
significantly different from 1.
"Supplementation with vitamin
C, vitamin E, or beta carotene offers no overall benefits in the
primary prevention of total cancer incidence or cancer mortality," the
authors conclude. "In our trial, neither duration of treatment nor
combination of the three antioxidant supplements had effects on overall
fatal or nonfatal cancer events. Thus, our results are in agreement
with a recent review of randomized trials indicating that total
mortality was not affected by duration of supplementation and single or
combined antioxidant regimens."
In an accompanying editorial,
Demetrius Albanes, M.D., of the National Cancer Institute, reviewed
data from previous randomized controlled trials that examined
supplement use and cancer incidence. He noted that while the trial data
reported by Lin are negative with respect to lowering cancer risk,
there is valuable information uncovered that should not be overlooked.
There was a trend for a reduction in colon cancer with vitamin E
supplementation, which has been observed in other studies.
Additionally, beta carotene use was associated with a modest excess of
lung cancer, which is consistent with previous reports.
trials or those with unexpected outcomes should not, however, be viewed
as failures; they have and will con¬tinue to shed light on the causes
of cancer and help us discover the means for its prevention," the
Article: Jennifer Lin, firstname.lastname@example.org, 617-278-0894
Editorial: NCI Press Office, email@example.com, 301-496-6641
Article: Lin J et al.,Vitamins C and E and Beta Carotene Supplementation and Cancer Risk: A Randomized Controlled Trial.
J Natl Cancer Inst 2009:101:14-23.
Editorial: Albanes D, Vitamin Supplements and Cancer Prevention: Where Do Randomized Controlled Trials Stand?
J Natl Cancer Inst 2009:101:2-4.
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