Green Tea Extract Keeps Arteries Unclogged

Antioxidant Extract Fights Development of Plaque in Mice

Medically Reviewed by Brunilda Nazario, MD on May 24, 2004

May 24, 2004 -- Green tea may hold the key to keeping hearts clog-free.

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 Circulation.

"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 plaque.

"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 release.