Chewing a stick of gum, especially cinnamon-flavored gum, may keep bad breath away, researchers report.

A new study has shown that cinnamon-flavored Big Red gum kills bacteria that are linked to bad breath. Researchers suspect that a plant oil called cinnamic aldehyde, which is used for flavoring cinnamon gum, helps kill bacteria.

But even gum without cinnamic aldehyde killed a substantial percentage of bad-breath bacteria, suggesting that other natural flavorings also play a role.

The research was supported by the Wrigley Company, which makes Big Red.

Bacteria in the mouth are thought to contribute to bad breath by producing substances called volatile sulfur compounds.

Dr. Christine Wu and colleagues at the University of Illinois at Chicago have found that several varieties of plant essential oils suppress the growth of bacteria that can cause cavities and oral infections.

“In laboratory tests, some of these oils also prevented the growth of three species of oral bacteria associated with bad breath and the production of volatile compounds that cause the unpleasant smell,” Wu said in a press release.

The next step for the researchers was to test the effect of plant essential oils in chewing gum.

They evaluated the effect of Big Red, which contains a variety of plant essential oils, including cinnamic aldehyde. The study also included a version of the gum that had the cinnamic aldehyde removed but still contained other plant essential oils. Participants also chewed a gum base that had neither flavors nor oils.

Wu and her colleagues collected saliva samples before and after the 15 people chewed gum for 20 minutes. They then compared pre- and post-chewing bacteria levels.

Bacteria levels dropped after chewing gum with and without cinnamic aldehyde.

Levels of bacteria that produce the sulfur compounds dropped by about 50 percent after chewing the gum with cinnamic aldehyde. Even without the cinnamon flavoring, bacteria levels dropped by about 40 percent after chewing gum.

But the unflavored variety of gum, which did not contain any plant oils, did not have an effect on bacteria levels.

The results of the research were presented last month at a meeting of the International Association for Dental Research in Honolulu, Hawaii.

“Our study shows that chewing gum can be a functional food, having a significant impact on oral hygiene over the short term, if it contains antimicrobial agents such as cinnamic aldehyde or other natural active compounds,” Wu said in the press release. “The product doesn’t just mask foul mouth odor. It eliminates the bacteria that cause it, at least temporarily.”

Although chewing gum reduced bacteria in the mouth, the study did not evaluate participants’ breath.