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Garlic And Onions Better
Than Leeks In Blocking
Carcinogen
University, Pa. -- July 2,
1997 -- In laboratory tests,
garlic and onions block the
formation of a potent
carcinogen better than their
milder cousin, the leek, a
Penn State study has found.
Dr. John Milner, professor
and head of the Department
of Nutrition in Penn State's
College of Health and Human
Development, is leader of
the study. He says the
results are consistent with
epidemiological evidence
from China which shows that
those who have a higher
consumption of vegetables
from the onion family have a
reduced cancer risk.
The Penn State results are
reported in the current
issue (Vol. 28, No. 1) of
the journal, Nutrition and
Cancer, in a paper titled,
"S-Allyl Cysteine Inhibits
Nitrosomorpholine Formation
and Bioactivation."
There is a growing body of
evidence that plants from
the garlic or Allium family,
which includes onions, leeks
and chives, are effective
cancer fighters, says
Milner. The Penn State
study, however, is the first
to show that not all Allium
foods are equal in their
ability to retard the
formation of cancer causing
compounds.
The researchers found that
water extracts of garlic,
deodorized garlic powder and
onions each blocked the
ability of two chemicals,
nitrite and morpholine, to
link to form N-nitrosomorpholine,
a known liver carcinogen.
The leeks' blocking ability,
on the other hand, was
minimal.
"Since deodorized garlic
powder and garlic produced
comparable results, the
benefits cannot relate to
odor causing constituents,"
Milner says.
N-nitrosomorpholine is a
member of the nitrosamine
family of chemicals, many of
which are potent
carcinogens. Most
nitrosamines are produced
naturally in the body from
nitrates and nitrites in
water and foods.
"Since garlic and onions can
block the formation of N-nitrosomorpholine,
it is likely it will reduce
the formation of other
nitrosamines, " Milner says.
The Penn State researchers
also found that a water
soluble, sulfur-containing
compound found in processed
garlic, called S-allyl
cysteine, also depressed the
formation of the carcinogen.
In addition, the sulfur
compound reduced N-nitrosomorpholine's
ability to alter DNA, the
genetic material present in
cells.
"The benefits of eating
garlic and onions is more
than a blocking of
nitrosamine formation but is
also due to blocking their
subsequent metabolism,
Milner says.
"Well over 90 percent of
nitrosamines are considered
carcinogens," Milner noted,
"anything you can do to
counteract their effect
should be important in
reducing cancer risk." The
study was supported, in
part, with grants from the
American Institute of Cancer
Research and Wakunaga of
America Co., Ltd.
Milner's co-authors are Mark
E. Dion, who earned his
master's degree at Penn
State, and Melanie Agler, a
Penn State undergraduate. |
