Green tea inhibits cancer growth
By Jeyling Chou
Feb. 17, 2005 9:00 p.m.
A UCLA study has further confirmed the potential and potency of
an anti-cancer agent brewed in a pot.
Green tea extract has been shown to selectively inhibit the
growth and spread of cancer cells, leaving normal cells
untouched.
An obstacle in cancer treatments is a means of targeting tumor
cells without damaging healthy tissue. The study, conducted with
green tea and bladder cancer cell lines, has shown promise in this
effect.
The properties of green tea have proven to yield many health
advantages.
“Most of the data seems to suggest that green tea is
beneficial not only for cancer but for cardiovascular disease as
well, based on epidemiological studies and animal model
studies,” said Jian Yu Rao, senior author of the study and an
associate professor of pathology and laboratory medicine.
The interdisciplinary research team, drawn from the Jonsson
Comprehensive Cancer Center, the School of Public Health, the
Center for Human Nutrition, and various other departments in the
School of Medicine, published its findings this week.
In cancer cells, green tea extract targets a protein responsible
for the motility and invasive properties of tumors, slowing their
growth and spread. The protein also regulates cell movement and
structure, and is not damaged in healthy cells.
The antioxidant effects of green tea have long been touted by
the American Cancer Society and other cancer research
organizations, but the exact mechanisms have yet to be pinpointed
before clinical application in patients.
“We tried to determine whether this would benefit the
patient who has bladder cancer to see if the green tea can prevent
the progression of the disease,” Rao said.
The next step would be to develop a measurable assay to
determine how a patient might respond to green tea extract, and to
track treatment progression.
Green tea has also been shown to have an effect on gene
expression that may be linked to cancer development. The irregular
gene expression characteristic of cancerous cells causes
uncontrollable cell division that is not regulated like normal
cells.
Loss of regulation occurs as cells age and DNA mutations
increase in frequency. Antioxidants like green tea can reverse the
damage to genetic material.
“The key question is how early this can be effective,
whether green tea can be beneficial for somebody who has very early
(genetic) changes,” Rao said.
Previous epidemiological studies conducted by UCLA researchers
have shown that regular drinkers of green tea are half as likely to
suffer from chronic gastritis, or inflammation of the stomach.
Frequent consumption of green tea also decreases the risk of
stomach cancer by 48 percent, according to a study published in
2001.
Researchers recommended three cups of green tea a day for
preventative effects.
