[Paleopsych] BH: Green Tea a Performance-enhancing Drug
checker at panix.com
Fri Jan 28 16:05:16 UTC 2005
Green Tea a Performance-enhancing Drug
Equivalent of four cups a day improves swimming endurance up to 24% in mice
while stimulating the use of fat as energy
1/27/2005 5:00 PM
Cup of Tea
Credit: Andrzej Burak
Sports drink: Green tea appears to boost exercise performance by
spurring the use of fat during endurance activities
Green tea may soon show up in locker rooms and doping tests after
being found to boost exercise endurance in mice up to 24% while
spurring the use of fat as energy.
While the finding is based on green tea extract (GTE) and is difficult
to extrapolate to human athletes, Japanese researcher Takatoshi Murase
estimates that to match the effects athletes weighing 75 kilograms
(165 pounds) would need to drink about four cups of green tea a
day--and over several weeks.
"One of our important findings," says Murase, "was that a single
high-dose of GTE or its active ingredients didn't affect performance.
So it's the long-term ingestion of GTE that is beneficial."
The study was conducted by Murase and colleagues at the Biological
Sciences Laboratories of Kao Corp. in Tochigi, Japan--a company
that makes green tea beverages and has been investigating the tea's
The researchers say their findings show that green tea extract can
boost exercise capacity and support the hypothesis that stimulating
the use of fatty acids can improve endurance.
While acknowledging that the impact of dietary interventions on
performance is controversial, the researchers note that compounds in
green tea called catechins have already been found to have various
These include counteracting obesity from a high-fat diet, for which
the researchers recently demonstrated evidence. This finding suggested
that catechins stimulate fat oxidation.
It's thought that this might improve exercise performance by allowing
the body to get energy from fat rather than carbohydrates during
To test the theory that catechins boost endurance capacity by
stimulating fat burning, the researchers used mice swimming in an
adjustable-current water pool. Some of the mice received no green tea
compounds, others received green tea extract and still others received
only a catechin in green tea known as EGCG.
Mice on no supplements could swim about 33 minutes before they were
exhausted. Mice on green tea extract consistently performed better
after the first week and by week nine those taking 0.5% green tea
extract by weight could swim 40 minutes compared to 33 for the
controls. A similar effect was observed in mice on EGCG, suggesting
that it was at least partly responsible for the benefits.
To support their theory about fat burning, the researchers found that
fatty acids in blood increased slightly but significantly in mice on
the supplements. They say that their findings suggest that green tea
extract enhanced the ability of muscle to use fatty acids as an energy
To avoid potential complicating factors in other studies, the
researchers controlled for possible influences of caffeine--a known
performance enhancer--and changes that might have affected the
The next steps are to determine the molecular mechanism by which green
tea stimulates fat burning and whether the antioxidant properties of
catechins mediate their effects on endurance capacity.
The research is reported in the American Journal of
Physiology--Regulatory, Integrative and Comparative Physiology.
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