Green Tea May Block Lung Cancer by BBC News Staff
"Drinking green tea may offer some protection against lung
cancer, say experts who studied the disease at a medical university
in Taiwan. The latest work in more than 500 people adds to growing
evidence suggesting the beverage has anti-cancer powers. In the
study, smokers and non-smokers who drank at least a cup a day cut
their lung cancer risk significantly, a US cancer research
conference heard. The protection was greatest for people carrying
certain genes. But cancer experts said the findings did not change
the fact that smoking is bad for health.
Green tea is made from the dried leaves of the Asian plant Camellia
sinesis and is drunk widely across Asia. The rates of many cancers
are much lower in Asia than other parts of the world, which has led
some to link the two. Laboratory studies have shown that extracts
from green tea, called polyphenols, can stop cancer cells from
growing. But results from human studies have been mixed. Some have
shown a protective effect while others have failed to find any
evidence of protection.
In July 2009, the Oxford-based research group Cochrane published a
review of 51 studies on green tea and cancer which included over
1.5 million people. They concluded that while green tea is safe to
drink in moderation, the research so far is conflicting about
whether or not it can prevent certain cancers.
Dr I-Hsin Lin, of Shan Medical University, found that among smokers
and non-smokers, people who did not drink green tea were more than
five times as likely to get lung cancer than those who drank at
least one cup of green tea a day. Among smokers, those who did not
drink green tea at all were more than 12 times as likely to develop
lung cancer than those who drank at least a cup a day.
Researchers then analysed the DNA of people in the study and found
certain genes appeared to play a role in the risk reduction. Green
tea drinkers, whether smokers or non smokers, with certain types of
a gene called IGF1, were far less likely to develop lung cancer
than other green tea drinkers with different types of this
gene.
Yinka Ebo, of Cancer Research UK, said the findings should not be
used as an excuse to keep smoking. "Smoking tobacco fills your
lungs with around 80 cancer-causing chemicals. Drinking green tea
is not going to compensate for that. Unfortunately, it's not
possible to make up for the harm caused by smoking by doing other
things right like eating a healthy, balanced diet. The best thing a
smoker can do to reduce their risk of lung cancer, and more than a
dozen other cancer types, is to quit."
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