Two new studies suggest that regular tea drinking can stave off unsociable mouth odors. Both were presented May 20 at the American Society for Microbiology's annual meeting in Washington, D.C.

Researchers at the University of Illinois at Chicago found the popular beverage contains compounds, called polyphenols, which halt the growth of odor-causing bacteria.

Bad breath is caused by malodorous volatile sulfur compounds produced by anaerobic bacteria that thrive in the back of the tongue and in the deep recesses of gums.

Polyphenols appear to hit halitosis -- the medical term for bad breath -- with a one-two punch by preventing the growth of those bacteria and then blocking their ability to produce sulfur compounds, the study suggests.

The researchers tested the drink's odor-fighting powers by incubating tea polyphenols with three species of bacteria associated with bad breath for 48 hours.

Using a range of concentrations typically found in several cups of black tea (16 to 250 micrograms per milliliter), they found the polyphenols inhibited the growth of bacteria.

Moreover, at even lower concentrations the polyphenols cut the formation of hydrogen sulfide, the smell-producing culprit, by 30 percent.

A second study by Pace University researchers found green tea extract also shows microbe-fighting properties that protect the mouth from disease-causing bacteria and viruses.

"Many toothpastes don't fight viruses. But when we add green tea, it's an amazing result: I get a 90 percent destruction of viruses," says study author Milton Schiffenbauer, a microbiologist and professor at Pace University in New York City.

Both studies are preliminary and have not been tested outside of the laboratory environment -- a fact that Dr. Jon Richter, director of the Richter Center for the Treatment of Bad Breath Disorders, says is a major weakness of the research.

"You can put just about anything on a petri dish with bacteria and show a decrease in growth. If they really want to see how these tea products affect bad breath they ought to take patients with bad breath and see if their condition gets better after drinking tea and run the study with controls," Richter says.

University of Illinois researchers are now doing just that -- testing the efficacy of a black tea rinse for bad breath on patients in a controlled trial.

More information

Learn about the causes and treatments for dragon breath at the American Dental Association or the University of Manitoba.