February 10 (HealthDay News) -- The same source of garlic's pungent aroma and taste may provide its benefits to health, scientists say.

They say an acid produced by the decomposition of an organic compound called allicin provides the food's health benefits.

It's long been suspected that allicin, which gives garlic its aroma and flavor, might also be a powerful antioxidant. But researchers haven't been able to determine how allicin works or how it compares to other antioxidants, which stop the damaging effects of free radicals on cells.

"We didn't understand how garlic could contain such an efficient antioxidant, since it didn't have a substantial amount of the types of compounds usually responsible for high antioxidant activity in plants, such as the flavonoids found in green tea or grapes," study leader Derek Pratt, a chemistry professor at Queen's University in Kingston, Ontario, Canada, said in a university news release. "If allicin was indeed responsible for this activity in garlic, we wanted to find out how it worked."

In a series of experiments, Pratt's team found that the decomposition of allicin produces sulfenic acid, which rapidly reacts with radicals.

"Basically, the allicin compound has to decompose in order to generate a potent antioxidant. The reaction between the sulfenic acid and radicals is as fast as it can get, limited only by the time it takes for the two molecules to come into contact. No one has ever seen compounds, natural or synthetic, react this quickly as antioxidants," Pratt said.

The study was published in the January issue of the journal Angewandte Chemie.

"While garlic has been used as an herbal medicine for centuries, and there are many garlic supplements on the market, until now, there has been no convincing explanation as to why garlic is beneficial," Pratt said. "I think we have taken the first step in uncovering a fundamental chemical mechanism which may explain garlic's medicinal benefits."

SOURCE: Queen's University, news release, Jan. 30, 2009