ACE Gene May Determine Green Tea's Ability to Guard
Against Breast Cancer
Participants: 297 people with breast cancer and
665 controls who did not have the disease.
Where: Singapore, China
Type of study: Case-control
Key information: One way in which green tea is
believed to fight breast cancer is by inhibiting free radical production caused
by a substance in the blood called angiotensin-II.
Angiotensin-II is "created" when it's converted from another
substance by an
enzyme called ACE (angiotensin-converting enzyme). Studies have shown that women who
have a "low activity" ACE gene (meaning they produce less ACE and
therefore less angiotensin-II) have a lesser risk of
developing breast cancer than those with a "high activity" ACE gene.
This made the researchers wonder if there was a link between green
tea (which fights the free radicals produced by angiotensin-II), the type of ACE
gene a woman has (which helps determine how much angiotensin-II her body makes), and
her risk of breast cancer.
Specifically, would green tea's ability to protect
against breast cancer depend on whether she had a "low activity" or a "high
activity" ACE gene?
Study methods: The researchers compared people
with breast cancer to healthy controls. All of the volunteers participated in
the Singapore Chinese Health Study.
What happened: There was no link between
consumption of green tea and the risk of breast cancer among women with a "low activity"
ACE gene.
However, among women with a "high activity" ACE
gene, green tea
demonstrated a statistically significant protective effect. Drinking green tea
at least once a week reduced their risk of developing breast cancer by a
stunning 71%, and
drinking it at least once a month reduced the risk by 67%.
These results suggest that if your body produces a lot of
angiotensin-II, drinking green tea can help reduce your risk of breast cancer.
But if your body doesn't produce much angiotensin-II, drinking green tea
probably won't make a difference in your breast cancer risk.
Researchers' conclusion: There was a statistically
significant decrease in risk of breast cancer among women with the
"high-activity" ACE gene who drank green tea at least monthly, and the risk
decreased even more if green tea was taken at least weekly. There was no such
effect on women with the "low activity" ACE gene.
These findings "highlight the importance of
genetically determined factors in evaluating the role of green tea intake in the
development of breast cancer."
Citation: Yuan JM, Koh WP, Sun CL, et al. Green
tea intake, ACE gene polymorphism and breast cancer risk among Chinese women in
Singapore. Carcinogenesis 2005;26(8):1389-94. (Click here to read PubMed study
abstract.)
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Nadine Taylor, M.S., R.D. presents
GreenTeaLibrary.com, the most comprehensive collection of scientific
information describing the health benefits of green tea.
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