A component in the green tea can protect the brain against the ravages of Alzheimer's disease, US scientists reported on Tuesday.

The researchers at the University of South Florida found the component, called epigallocatechin-3-gallate (EGCG), can prevent Alzheimer's-like neurodegenerative disease process in the brains of genetically modified mice. Their paper was published in the Sept. 21 issue of the Journal of Neuroscience.

In earlier studies, scientists had found this ingredient, a major antioxidant in green tea, can protect against certain cancers. Now the researchers said that EGCG decreases production of beta-amyloid, an Alzheimer's-related protein that accumulates abnormally in the brain and lead to nerve damage and memory loss.

This reduction in beta-amyloid was observed both in cell cultures and a mouse model for Alzheimer's disease. After treating Alzheimer's mice for several months with daily injections of pure EGCG, the researchers observed a dramatic decrease of brain-clogging Alzheimer's plaques by up to 54 percent.

EGCG appears to block the initial process by which the Alzheimer's-related protein is formed in brain cells, the researchers said.

"The findings suggest that a concentrated component of green tea can decrease brain beta-amyloid plaque formation," said senior study author Jun Tan, an assistant professor at the University of South Florida.

"If beta-amyloid pathology in this Alzheimer's mouse model is representative of Alzheimer's disease pathology in humans, EGCG dietary supplementation may be effective in preventing and treating the disease."

But the researchers noted that drinking green tea alone would not likely have a beneficial effect through the same mechanism.

Green tea contains many antioxidants, including those known as flavonoids that can protect against free radical damage to the brain. However, some flavonoids in green tea actually oppose naturally-occurring EGCG's ability to prevent the harmful build-up of beta-amyloid, according to their paper.

Thus, green tea extract selectively concentrating EGCG would be needed to override the counteractive effect of those flavonoids, the researchers said, noting that a new generation of dietary supplements containing pure EGCG may lead to the greatest benefit for treating Alzheimer's disease.

Humans would likely need 1500 to 1600 milligrams of EGCG daily to approximate the injection dosage that benefited the Alzheimer's mice. That dosage, already been studied in healthy human volunteers, was found to be safe and well tolerated, according to the researchers.