If there were a prize for achievement in the world of liquid nutrition, it would have to go to green tea. The reputations of other beverages—coffee, alcohol and milk, for example—have had their ups and downs. But so far no one has found a sinful side to green tea.

A study may have those other popular beverages turning, well, green with envy.

Researchers find that green tea may actually help prevent Alzheimer's disease, a degenerative brain disorder that leads to dementia and eventual death. The disease is characterized by brain-clogging tangles of proteins called plaques. So far, there is no cure.

According to a University of South Florida study of mice, a substance in green tea called EGCG (epigallocatechin-3-gallate) may reduce and even prevent the formation of these plaques. The research, published in The Journal of Neuroscience, is the first to show that the green-tea chemical has such a strong effect.

EGCG belongs to a class of powerful substances known as antioxidants. They are nutritional disease-fighters. Scientists believe antioxidants neutralize free radicals of oxygen-unstable molecules given off by the body's many metabolic actions. Free radicals are drawn to, and damage, fat-rich areas of the body, including the membranes of nerve and brain cells, which are primarily made of lipids.

Despite the study's promising results, the researchers are quick to note that much more work must be done to understand exactly how EGCG exerts it beneficial effects. It's still unclear whether blocking the development of Alzheimer's plaques will actually relieve the devastating symptoms of Alzheimer's disease, as the illness' progression is poorly understood.

While green tea may be a nutritional over-achiever, other tea varieties like black and oolong are no slouches either. They're in the same family, after all. True teas—that is, not herbal varieties—like black, oolong and green tea come from only one source: the leaves of the Camellia Sinensis plant. The major difference between varieties is in their preparation; specifically, how long the leaves are aged before they are dried. Black tea is aged the most, green tea the least.

The process of aging of tea leaves decreases the amount of antioxidants they contain, which seems to explain why green tea is a more powerful disease fighter than other teas.

But don't start drinking green tea with every meal just yet. Unfortunately for both green tea aficionados and Alzheimer's sufferers, the study revealed one gap in green tea's armor: you can't get the complete cerebral protection of its primary compound EGCG by simply sipping a few cups a day. The research suggests that other antioxidants present in green tea actually counteract EGCG's ability to block the Alzheimer's protein deposits. Consequently, dietary supplements of the purified compound may be the best bet for treating the disease in the future.

Jun Tan, the study's lead researcher, notes that the purified compound is already available. "You can go to the store, buy the pills and take EGCG," he says. "But this is not what we're immediately suggesting."

Tan urges caution because scientists do not know what dosage might be helpful—or even harmful. It's important that scientists first perform clinical trials to prove that EGCG is safe and effective in humans.

In the meantime, however, Tan still gives drinking green tea the thumbs up. Although it alone may not be enough to fully safeguard against Alzheimer's disease, Tan recommends it for everyone and says he and his co-workers drink it every day.