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Nutrition, Vitamins & Supplements for Seniors
JAMA Review Saying Some Antioxidants Increase Death
Risk Draws Attention
NBC Today explores 'Can taking vitamins be
dangerous?'
 March 21, 2007 The NBC Today show
this morning followed up a
report in the Journal of the American Medical Association,
warning that the antioxidant supplements beta carotene, vitamin A, and
vitamin E may increase the risk of death, with an analysis by their
nutritionist, Joy Bauer, of this report and her advice on vitamins. She
says, "These results certainly sound disturbing," but she points out
many health experts criticize the study.
Bauer also notes that the information is not new
but the review of results of 68 previous studies.
The article in the February 28 issue of JAMA says
the meta-analysis of previous studies contradicts claims of disease
prevention by these antioxidant supplements.
Many people take antioxidant supplements, believing
they improve their health and prevent diseases. Whether these
supplements are beneficial or harmful is uncertain, according to the
article.
Goran Bjelakovic, M.D., Dr.Med.Sci., of the Center
for Clinical Intervention Research, Copenhagen University Hospital,
Copenhagen, Denmark, and colleagues conducted the analysis of previous
studies to examine the effects of antioxidant supplements - beta
carotene, vitamins A and E, vitamin C (ascorbic acid), and selenium - on
all-cause death of adults included in primary and secondary prevention
trials.
Using electronic databases and bibliographies, the
researchers identified and included 68 randomized trials with 232,606
participants in the analysis.
The authors also classified the trials according to
the risk of bias based on the quality of the methods used in the study,
and stratified trials as low-bias risk (high quality) or high-bias
risk (low quality).
In an analysis that pooled all low-bias risk and
high bias risk trials, there was no significant association between
antioxidant use and mortality.
In 47 low-bias trials involving 180,938
participants, the antioxidant supplements were associated with a 5
percent increased risk of mortality.
Among low-bias trials, use of beta carotene,
vitamin A, and vitamin E was associated with 7 percent, 16 percent and 4
percent, respectively, increased risk of mortality.
There was no increased mortality risk associated
with vitamin C or selenium use.
Our systematic review contains a number of
findings. Beta carotene, vitamin A, and vitamin E given singly or
combined with other antioxidant supplements significantly increase
mortality. There is no evidence that vitamin C may increase longevity.
We lack evidence to refute a potential negative effect of vitamin C on
survival. Selenium tended to reduce mortality, but we need more research
on this question, the authors write.
Our findings contradict the findings of
observational studies, claiming that antioxidants improve health.
Considering that 10 percent to 20 percent of the adult population
(80-160 million people) in North America and Europe may consume the
assessed supplements, the public health consequences may be substantial.
We are exposed to intense marketing with a contrary statement, which is
also reflected by the high number of publications per included
randomized trial found in the present review.
There are several possible explanations for the
negative effect of antioxidant supplements on mortality. Although
oxidative stress has a hypothesized role in the pathogenesis of many
chronic diseases, it may be the consequence of pathological conditions.
By eliminating free radicals from our organism, we interfere with some
essential defensive mechanisms
Antioxidant supplements are synthetic
and not subjected to the same rigorous toxicity studies as other
pharmaceutical agents. Better understanding of mechanisms and actions of
antioxidants in relation to a potential disease is needed, the
researchers conclude.
On the Today Show, Bauer advised, "Remember that
the study examined supplements, not food. No one is disputing the health
benefits of fruits and vegetables, which are super-rich in antioxidants,
as well as other nutrients you just cant find in a pill."
She said, however, "People should stop taking
MEGA-doses of antioxidants unless there's a real reason for taking
them
. and thats something to work out with your personal doctor."
"On the other hand," she adds, "I do think most
people will benefit from a basic multivitamin to fill in any potential
nutrient gaps in their diets."
>>
More information at NBC Today, click here
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