Light for Green Tea
(HealthScoutNews) -- If a group of Chinese researchers are right,
green tea may offer important protection against Parkinson's disease
-- a neurodegenerative disorder that made headlines when it was
diagnosed in both actor Michael J. Fox and boxing legend Muhammad
The new finding, reported today at the annual meeting of the American
Academy of Neurology in Denver, explains how ingredients plentiful
in green tea can help the flow of a brain chemical that's at the
heart of this devastating disease.
"In our study, we demonstrate the inhibitory effects of
green tea polyphenols," on mechanisms directly involved in
Parkinson's disease, says study author Dr. Tianhong Pan, a researcher
from China who was working at Baylor College of Medicine in Houston
during the study.
Pan says she and her colleagues in China began the animal study
-- a joint effort between the National Cancer Institute and the
Chinese government -- because of the lower rates of Parkinson's
disease among populations where green tea is heavily consumed.
"The prevalence of Parkinson's disease was lowest in Asia
and Africa, where green tea is commonly consumed, so it seems
that there is some relationship between green tea consumption
and the occurrence of [this disease]," Pan says.
For neurologist Dr. Souhel Najjar, this is the first research
to document the mechanism by which green tea can protect the brain.
"That mechanism involves the transport of the brain chemical
dopamine, which plays a key role in Parkinson's disease,"
says Najjar, a Parkinson's disease specialist.
Proving green tea can work on that transport system could be
key to learning how to prevent the disease, Najjar says, who adds
it could also open the door to new treatment strategies.
Pan agrees: "The results suggest that green tea may have
potential both in the treatment and protective effects in Parkinson's
The mechanism explored in this study involved the transport
of dopamine from the area of the brain where it is made to a second
area where it is utilized, movement that is critical in Parkinson's
"Normally, dopamine is made an area of the brain called
the substantia nigra, and it travels a pathway to a second area
of the brain known as the striatum," Najjar says. Sometimes,
however, too much of the dopamine flows back into the substantia
nigra. That leaves the striatum with less dopamine than it needs
to function properly.
Because dopamine helps muscles move smoothly and efficiently,
when a deficiency occurs, symptoms of Parkinson's develop -- including
muscle rigidity and tremors.
In the new study, however, researchers demonstrated that compounds
known as polyphenols can block the back flow of dopamine, so the
transport continues, unhampered, from one area of the brain to
"By keeping the transport of dopamine from being disrupted,
polyphenols might be able to reduce the risk of Parkinson's disease,
as well as reduce the progression of the disease in those already
affected, " Najjar says.
Although both doctors are optimistic, no one is certain the
results will apply to humans. Pan's group tested levels of dopamine
in mice, and then treated some with polyphenols while leaving
They then injured the specific neurons or brain cells linked
to Parkinson's disease in all of the mice, and measured dopamine
The result: Those mice treated with polyphenols appeared to
be protected from the assault on brain cells. Pan reports polyphenols
were able to "inhibit the uptake of dopamine
the dopamine transporter."
"In this way, green tea may serve to protect against Parkinson's,
particularly in the face of toxic elements that may be linked
to this disease," Najjar says.
However, can drinking green tea help people as much as it helps
"Although green tea polyphenols have numerous biological
effects in vitro, and epidemiological studies have shown some
health benefits in tea consumption, what is not clear at this
time is whether pharmacologically effective doses of green tea
polyphenols can be attained in blood or tissues simply by consuming
tea infusions," Pan says.
Najjar says it's possible, but based on this study "there
is not enough evidence to make any kind of recommendation."
In addition to green tea, polyphenols are found in black tea,
grapes, red wine, chocolate and other plant sources.
What To Do
To learn more about Parkinson's disease, you can visit the Parkinson's Disease Foundation.
For more information on the health benefits of green tea and
other sources of polyphenols, check out University of Shizuoka,
Reference Source 101