NEW YORK (Reuters Health) – While smoking is a well-known
cause of heart disease and lung cancer, the rates of these
diseases have remained inexplicably low in Asian countries
where smoking is common. But researchers say there is growing
evidence that green tea is one piece of the puzzle.
Writing in the Journal of the American College of Surgeons,
Yale University researchers detail the body of evidence linking
green tea to better heart health and a lower risk of cancer.
No one is suggesting that smokers ignore the danger of the
habit and simply drink green tea. But research indicates that
the tea’s high concentration of antioxidants called catechins
may offer a range of health benefits, according to Dr. Bauer E.
Sumpio and his colleagues at the Yale University School of
Medicine in New Haven, Connecticut.
Antioxidants help quench molecules known as oxygen free
radicals that, in excess, can damage body cells and potentially
lead to disease. Free radicals are natural byproducts of normal
body processes, but they are also generated by external sources
like tobacco smoke.
In Japan, China and other Asian countries, it is a social
custom to drink green tea, which is less processed — and
richer in catechins — than the black tea commonly consumed in
the West.
And it’s possible that this habit helps explain the
so-called “Asian paradox,” according to Sumpio and his
colleagues.
This paradox becomes clear when looking at global health
statistics, the researchers note. For example, for every
100,000 U.S. men, 348 will die of coronary heart disease each
year. The figure for Japanese men is 186, despite the nation’s
higher rate of smoking.
Coronary heart disease (CHD) develops when the arteries
feeding the heart become hardened and narrowed due to the
buildup of cholesterol-containing plaques on the artery walls.
According to Sumpio’s team, lab research suggests that that
green tea catechins — particularly one called EGCG — may help
thwart the CHD process through their effects on “bad” LDL
cholesterol.
The antioxidants may also help keep artery walls
functioning smoothly, as well as inhibit blood cells from
sticking together and forming clots.
Similarly, lab studies suggest that EGCG and other green
tea antioxidants may block tumor formation or growth in a
number of ways. This may, according to the researchers, help
explain why the lung cancer death rate in Korea is unexpectedly
low.
The rate of lung cancer death among Korean men is less than
40 per 100,000, versus 67 per 100,000 among U.S. men. The
difference among women is more stark: 13 per 100,000 in Korea,
compared with 45 per 100,000 in the U.S.
This is despite the fact that 37 percent of Korean adults
smoke, while only 27 percent of Americans do.
The global disease patterns are not that simple, however;
China has a higher CHD death rate than the U.S. and many other
Western nations, and the rate of death from lung cancer is
about the same among Japanese and American men. Green tea,
according to Sumpio, is no substitute for kicking the smoking
habit.
“Smoking cessation is the best way to prevent
cardiovascular disease and cancer,” he said in a statement.
SOURCE: Journal of the American College of Surgeons, May
2006.
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