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Vitamin's effect on cancer varies
by smoker status
New York -
High intake of beta-carotene seems to decrease the risk of
tobacco-related cancers among people who've never smoked, but to
increase the risk among current or past smokers, new research
suggests. Although the findings are based on a study of women, the
researchers believe that similar results would be obtained in men.
"Based on the findings from our study
and others, I would advise against beta-carotene supplements for
current or past smokers," senior author Dr. Marie-Christine
Boutron-Ruault, from INSERM in Villejuif, France, told Reuters Health.
"For beta-carotene-rich foods, the message is less clear, since they
often contain other vitamins that may counteract the interaction of
beta-carotene with smoking."
The new study, which is reported in
the Journal of the National Cancer Institute, involved an evaluation
of beta-carotene intake for 59,910 women who were followed for about 7
years to assess cancer occurrence. During follow-up, 700 women
developed tobacco-related cancers, such as lung cancer or head and
neck cancer.
Among never smokers, consuming a diet
containing moderate amounts of beta-carotene cut the risk of cancer by
up to 28 percent. Taking beta-carotene supplements reduced the risk by
56 percent.
Just the opposite effect was seen in
current or past smokers. In this group, consuming a diet containing
moderate amounts of beta-carotene increased the risk of cancer by up
to 43 percent. Taking beta-carotene supplements more than doubled the
risk of cancer.
"We were surprised at the completely
opposite effect high beta-carotene intake had on cancer risk depending
on whether you had never smoked or ever smoked," Boutron-Ruault noted.
"We plan on doing a larger study with
more cancer cases, a larger variety of doses of beta-carotene and
tobacco, and both men and women" to verify and expand on the current
findings, she added. -- Reuters
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