Epigallocatechin gallate, or EGCG, is a component of green tea that can block the ability of the AIDS virus to hijack and destroy immune-system cells.

EGCG, the compound that gives green tea its color, is a flavonoid that also has anti-cancer, anti-microbial and anti-inflammatory properties. EGCG-based cancer drugs already are in clinical trials.

Researchers have known that EGCG inhibits the progression of HIV for at least a decade, but the precise mechanism was unknown. New experiments have recently demonstrated that EGCG binds itself to the exact spot HIV needs to infect a healthy T-cell, a kind of white blood cell crucial to fighting infections.

Normally, a surface protein on HIV called GP120 locks into a special "pocket" on the surface of susceptible host cells called CD4 T-cells. HIV then releases its genetic material into the healthy cell, and the infected cell begins producing more viruses. ECGC locks into the pocket first, preventing HIV from entering.

The amount of EGCG needed to block the progression of HIV is equivalent to that received from drinking two cups of green tea. However, the researchers did not recommend drinking green tea to slow down AIDS, positing that the chemical would need to be part of a cocktail of drugs.