Green Tea Extract Keeps Arteries Unclogged
Antioxidant Extract Fights Development of Plaque in Mice
May 24, 2004 -- Green tea may hold the key to keeping hearts
Powerful antioxidants make up a third of the weight of dried
tea leaves. The main one of these good-for-you compounds is called EGCG (or, if
you're good at tongue twisters, epigallocatechin-3-gallate).
New mouse studies show that EGCG can slow the build-up of
artery-clogging plaque. Yes, you've heard something like this before. Animal
studies often show that antioxidants keep arteries from clogging. Human trials,
however, are often disappointing.
That may soon change. What's different about this study is that
it indicates the timing of green-tea-extract treatment makes a world of
difference. Cardiologist Kuang-Yuh Chyu, MD, PhD, of Cedars-Sinai Medical
Center, Los Angeles, and colleagues report the findings in the May 25 issue of
"Most animal experiments evaluating the effects of
antioxidants are started when the animals are young. Randomized clinical trials
typically enroll adult patients with varying stages of plaques," Chyu says
in a news release. "This discrepancy supports speculation that antioxidant
treatment affects early but not later stages of plaque development."
Chyu's team studied mice fed a high-cholesterol diet and then
given a plaque-inducing injury to their main heart artery. After the
plaque-induced injury, some of the animals started getting injections of the
green tea extract EGCG.
It worked. On day 21, the animals had 55% less plaque than
those animals not given green tea extracts. By day 42, they had 73% less
plaque. But the treatment had no effect when given to animals with fully mature
"It appears that antioxidant therapy would have therapeutic
benefits only if initiated during a critical window very early in the formation
of plaque," Chyu says.
Prediman K. Shah, MD, the study's senior researcher and
director of the Cedars-Sinai cardiology division, says the findings move
scientists closer to finding ways of preventing human heart disease.
"We look forward to developing and fine-tuning innovative
prevention and treatment techniques in the future," Shah says in a news