WASHINGTON (Reuters) September 20, 2005 - An ingredient in green tea that researchers think might fight cancer may also protect the brain from the memory-destroying Alzheimer’s disease, a study released Tuesday said.

Scientists injected mice with an antioxidant from green tea called epigallocatechin-3-gallate (EGCG) and said it decreased production of beta-amyloid, a protein that forms the plaques that clog the brains of Alzheimer’s victims.

Several months of injections reduced plaque formation by as much as 54 percent, researchers from the University of South Florida wrote in the Journal of Neuroscience. The mice had been genetically programmed to develop an Alzheimer’s-like disease.

Alzheimer’s is a progressive disorder that causes memory loss and afflicts an estimated 4.5 million people in the United States and millions more globally.

Drinking ordinary green tea may not lead to the same plaque reduction seen in the study because other ingredients in the beverage appear to block EGCG’s benefits, said Dr. Jun Tan, the study’s senior author and director of the neuroimmunology laboratory at the Silver Child Development Center in the University of South Florida’s psychiatry department.

Supplement pills containing EGCG might help, he said. Scientists are also trying to develop a tea with a high concentration of EGCG that could offer health benefits.

Other studies have shown EGCG may prevent certain cancers and could block the spread of the HIV virus that causes AIDS.

Humans would probably need 1,500 to 1,600 milligrams per day of EGCG to get the amount that helped mice in the Alzheimer’s study, Tan said.

Researchers have tested the safety of those doses in people and found no major side effects, he said.

The next step for researchers is to test an oral form of EGCG in mice and see if it protects the animals’ memory, he said. “If those studies show clear cognitive benefits, we believe (human) trials of EGCG to treat Alzheimer’s disease would be warranted,” Tan said.

The study was funded by the University of South Florida College of Medicine Faculty Start-Up Funds, the Johnnie B. Byrd Sr. Alzheimer’s Center & Research Institute, the National Institute of Neurological Disorders and Stroke and the Alzheimer’s Association.