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Antioxidants and Cancer
7/9/00
Antioxidants such as Vitamin
C, Vitamin E, and beta-carotenes are substances that can neutralize harmful
elements called "radicals" in the body.
This role has been touted for a long time to be a possible potent
"natural" body defense against cancer.
Many hundreds of studies have been done to investigate whether in
practice this is actually true.
While some studies did show a small benefit, other large studies showed a
possible detriment (and in some cases, an increase in the rate of cancer
formation) with intakes of large quantities of these substances.
The
Institute
of Medicine (which comprises part of the National
Academy of Sciences) recently looked into this subject. The consensus was that there was
insufficient evidence that consumption of mega-doses of antioxidants in the diet
and through supplements can prevent chronic diseases (such as cancer.)
The
committee was chaired by Norman I. Krinsky, PhD, a professor of biochemistry at
the Tufts
University School of Medicine.
The
committee recommended minimum and maximum daily doses for some substances. For Vitamin E, Men and women should
minimally obtain 15mg daily from diet or supplements. The maximum daily quantity should not
exceed 1 gram per day. For
Selenium, a minimum daily intake of 55 micrograms per day and a maximum of 400
micrograms per day were recommended.
For Vitamin C, a minimum daily intake of 75 mg for women and 90 mg for
men were recommended. Intake should
be increased by 35 mg in people who smoke.
The maximum daily amount should be 2 grams. In this committee's conclusion, they
determined there are not enough studies to determine that carotenoids are
actually of benefit and no daily minimum or maximum doses were recommended.
While it is good to note
that there is work being done to come up with consensus guidelines in this area,
there are still many points of controversy. In the meantime, common sense should be
your guide. If you have a
reasonably well balanced diet, supplements may not be required. If there is a lack of variety in your
dietary intake then supplements would be a reasonable choice. I certainly don't advocate mega-doses of
any particular substance. Remember,
too much of a good thing can actually be toxic!
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