Hops used to brew beer may have some health benefits but researchers warn against expecting any significant effect by drinking a few cold ones.

Scientists at Oregon State University's Linus Pauling Institute have found a class of compounds called flavonids neutralize "free radicals" — rogue oxygen molecules that can damage cells.

One of those flavonids, a compound called xanthohumol, is found only in hops. It may help prevent some forms of cancer, researchers say.

Some beers already have higher levels of flavonids than others. The lager and pilsner beers commonly sold in domestic U.S. brews have fairly low levels of these compounds, but some porter, stout and ale brews have much higher levels.

Still, the level of the compound in beer is generally considered too low to have any significant preventive effect.

"We can't say that drinking beer will help prevent cancer," said Fred Stevens, OSU assistant professor of pharmacy and scientist in the Linus Pauling Institute.

Hops, from a flowering plant, are used by brewers as a bittering agent in beer. Xanthohumol is a yellow substance that was first discovered in hops in 1913.

But its health effects were not known until the 1990s, when Stevens and colleagues started studying the flavonoid compound. In cell cultures and animal studies, xanthohumol targeted various types of cancer, including breast, colon and ovarian.

His original work, along with new developments in the anti-cancer properties of xanthohumol made during the past decade, was reviewed last year in the journal Phytochemistry.

Now Stevens is collaborating with fellow Linus Pauling Institute scientist Emily Ho to investigate the effects of the flavonoid on prostate cancer cells.

"When we give the flavonoid to cancer cells, it seems to slow their growth, which is what you want to do for cancer," said Ho, who is also an assistant professor in OSUs department of nutrition and exercise sciences.

Although the tiny amounts of xanthohumol found in beer have little preventive value, Stevens thinks it may be possible in the future for drug companies to develop pills containing concentrated doses of the flavonoid.