Green tea extract boosts exercise endurance 8-24%

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From: " pureheart " <pureheart@...>

Subject: Green tea extract boosts exercise endurance 8-24%

Date: 29 Jan 2005 12:33:52 -0800

Contact: Mayer Resnick

mresnick@...

Office: 301-634-7209

Cell: 301-332-4402

American Physiology Society

Green tea extract boosts exercise endurance 8-24%, utilizing fat as

energy source

Swimming endurance improvement comes from equivalent of four cups of

tea a day over 10 weeks

BETHESDA, Md. (Jan. 27, 2005) - Now that even baseball players may

need to seek new, more natural performance aids, will Japanese green

tea sets become standard in dugouts and athletic training tables

around

the world?

A new study tested the effect of regularly taking green tea extract

(GTE) and found that over 10 weeks, endurance exercise performance

was

boosted up to 24% with 0.5% GTE supplementation, and 8% with 0.2%

by-weight addition to food.

Reporting in the online edition of the American Journal of

Physiology-Regulatory, Integrative and Comparative Physiology

researchers at the Biological Sciences Laboratories of Kao Corp.,

Tochigi, Japan, said the 8-24% increase in swimming time-to-

exhaustion

was " accompanied by lower respiratory quotients and higher rates of

fat

oxidation. "

The results " indicate that GTE is beneficial for improving endurance

capacity and support the hypothesis that the stimulation of fatty

acid

utilization is a promising strategy for improving endurance

capacity, "

according to the study entitled, " Green tea extract improves

endurance

capacity and increases muscle lipid oxidation in mice. " Research was

conducted by Takatoshi Murase, Satoshi Haramizu, Akira Shimotoyodome,

Azumi Nagasawa and Ichiro Tokimitsu, working at Kao Corp., a Japanese

maker of healthcare products, including green tea beverages.

Results came from the equivalent of about 4 cups of tea a day

Although it's difficult to extrapolate from mice eating GTE as a food

supplement to a major leaguer or Olympic swimmer sipping green tea,

the

study's lead author, Takatoshi Murase said: " We estimate that an

athlete weighing 75 kilograms (165 pounds) would have to drink about

four cups (0.8 liter) of green tea daily to match the effect in our

experiments. "

" One of our important findings, " Murase pointed out, " 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. " (Murase

based his calculations of mouse-to-human tea/GTE consumption

equivalents on work his lab is doing on the anti-obesity effects of

GTE

on mice and humans.)

In an era when professional and amateur athletes are always looking

for

ways to improve performance, and most people want to improve their

health and exercise capabilities, " the efficacy of dietary

interventions is still controversial, " the authors acknowledge. They

note that green tea and cacao contain a class of polyphenols called

catechins, which consist mainly of epigallocatechin gallate (EGCG),

epicatechin gallate and gallocatechin gallate. Catechins have been

reported to have various physiological and pharmacological properties

over the years.

The Kao lab " recently demonstrated that the long-term consumption of

tea catechins was beneficial in counteracting the obesity-inducing

effects of a high-fat diet, and that their effects may be attributed,

at least in part, to the activation of hepatic lipid catabolism " in

mice. " Overall, " the authors said, " observations so far suggest that

thermogenesis and fat oxidation are stimulated by the intake of

catechins. "

Working hypothesis and study methods

" To confirm our hypothesis that catechins affect endurance exercise

capacity (i.e. time to exhaustion) by increasing lipid utilization,

in

this study we examined the effect of catechin-rich GTE intake on the

endurance capacity of Balb/c mice swimming in an adjustable-current

water pool. We also analyzed changes in energy metabolism, especially

lipid metabolism. We demonstrated that GTE intake improved endurance

capacity and this was accompanied by an increase in lipid catabolism.

Our results support the hypothesis that stimulation of lipid

metabolism

is a promising strategy for improving the capacity for endurance

training. "

The ideas for the experiment come from the fact that " skeletal

muscles

utilize carbohydrates, lipids and amino acids as energy sources, but

the ratio in which they are used varies with the intensity of

exercise

and the level of fitness " as well as the type of exercise involved.

For

instance " during endurance exercise, excess glucose is undesirable

because it induces insulin secretion, which in turn simultaneously

inhibits lipid metabolism and stimulates lactate production.

Conversely, enhanced availability and utilization of free fatty acids

are considered to reduce carbohydrate utilization, which in turn

spare

glycogen and suppresses lactate production and results in an increase

in endurance. "

To test what effects GTE and its components would have on endurance

exercise, the researchers ran two experiments. In the first, swimming

endurance capacity was measured at eight weeks of age and the mice

were

divided into four groups of 10 each. All subjects had unlimited

access

to water for exercise. For 10 weeks, controls ate a standardized diet

only, while experimental animals had this diet supplemented with 0.2%

and 0.5% GTE by weight. During this period experimental mice were

exercised in a pool twice a week, but non-exercise mice weren't.

The second experiment was similar to the first but the experimental

groups received a diet containing 0.1% to 0.5% EGCG for 10 weeks.

At the beginning of the experiment, the mice swam about 26 minutes

until they were exhausted. After 10 weeks on the training regimen,

the

time-to-exhaustion for the exercise-control mice (no GTE or EGCG

supplement) rose to about 33 minutes, showing the effects of unaided

practice on endurance capacity. From the first week of the

experiment,

the mice on GTE showed greater improvement compared with the

exercise-controls. By week eight, the improved performance of mice on

0.5% GTE was significantly better (39 minutes) than the

exercise-controls (33 minutes) at a 0.05 level, while improvement in

weeks 9 and 10 (40 minutes vs. 33 minutes) were significant at the

0.01

level.

GTE effects not matched by EGCG alone suggesting other additional

influences

In the global search for enhanced athletic performance (and health

and

fitness), the Kao team said they " have shown that GTE improved

endurance capacity and that the improvement was dose-dependent. A

similar effect was observed in mice fed EGCG, a major constituent of

GTE, suggesting that the effects of GTE were mediated at least in

part

by EGCG.

" However, because the effects of EGCG appear weak compared with those

of GTE, we cannot rule out a possible contribution from other

components of GTE. Although long-term intake of GTE enhanced

endurance

capacity, no marked effects were observed after a single dose of GTE,

suggesting that some biochemical changes induced by habitual GTE

intake, such as up-regulation of muscular beta-oxidation, contributed

to the improvement in endurance capacity. "

The study found that plasma NEFA (non-esterified fatty acid) measured

immediately after exercise slightly, but significantly, increased in

mice fed tea catechins. Though they concede that the effect of plasma

fatty acid level on endurance capacity is controversial, they say

that

increased supply of circulating fatty acids would " induce the uptake

of

fatty acids, and thereby stimulate lipid metabolism in muscle. "

Indeed, lab results showed that muscular beta-oxidation was higher in

GTE-fed mice (compared with non-exercise and exercise-control mice),

" suggesting that GTE enhanced the capacity of muscle to catabolize

lipids and utilize fatty acids as an energy source. " Conversely, GTE

lowered plasma lactate concentrations, which would be raised by

glycogen breakdown and glycolytic flux, they note.

Taken together the experimental results " suggest that habitual

exercise

and the intake of GTE enhance fatty acid availability, catabolism and

utilization in muscle, and this is accompanied by a reduction in

carbohydrate use, which together result in prolonged swimming times

to

exhaustion. "

Controlling for caffeine

Kao researchers controlled for possible influences of caffeine and

possible weight-fat changes that might affect buoyancy.

Aware that previous studies were criticized by the possible role of

caffeine on fatty acids and exercise, the Kao researchers reduced the

amount of caffeine in supplements. " In addition, we observed no

changes

in plasma NEFA level under resting conditions, suggesting that

caffeine-stimulated lipolysis did not occur under these conditions.

Thus our results overall suggest that the effects observed in this

study are not attributable to caffeine. In particular, our findings

that purified EGCG improved endurance capacity supports this

conclusion. "

Next steps

# The " precise molecular mechanism by which GTE stimulates fatty acid

metabolism is unclear at present (and) remains to be elucidated. "

# For instance, the researchers wrote, " it is possible that the

anti-oxidant properties of tea catechins mediate their effects on

endurance capacity. "

# And finally they noted: " Although the clinical efficacy of GTE has

not yet been confirmed in human studies, our results suggest that GTE

may be a useful tool for improving endurance capacity. "

###

Source and funding

The study, " Green tea extract improves endurance capacity and

increases

muscle lipid oxidation in mice, " was conducted by Takatoshi Murase,

Satoshi Haramizu, Akira Shimotoyodome, Azumi Nagasawa and Ichiro

Tokimitsu, appears in the online edition of the American Journal of

Physiology-Regulatory, Integrative and Comparative Physiology,

published by the American Physiological Society.

All researchers work at the Biological Science Laboratories of Kao

Corp., Tochigi, Japan, which makes healthcare products, including

green

tea beverages.

Editor's note: A copy of the research paper by Murase et al. is

available to the media. Members of the media may obtain an electronic

version and interview members of the research team by contacting

Mayer

Resnick at the American Physiological Society, 301.634.7209, cell

301.332.4402 or mresnick@....

The American Physiological Society was founded in 1887 to foster

basic

and applied bioscience. The Bethesda, land-based society has more

than 10,000 members and publishes 14 peer-reviewed journals

containing

almost 4,000 articles annually.

APS provides a wide range of research, educational and career support

and programming to further the contributions of physiology to

understanding the mechanisms of diseased and healthy states. In May,

APS received the Presidential Award for Excellence in Science,

Mathematics and Engineering Mentoring (PAESMEM).

http://www.eurekalert.org/pub_releases/2005-01/aps-gte012705.php