Wine Helps Kill Bad Oral Bacteria, Study Finds

Recent research at the University of Pavia in Italy has found that both white wine and red wine may help prevent the proliferation of streptococci, a type of bacteria associated with cavities, tooth decay and sore throats.

Oral strains of streptococci are responsible for the formation of dental plaque which, if left unchecked, can lead to cavities and periodontal disease. In the throat, these strains cause the burning, red inflammation known as strep throat. "Our findings seem to indicate that wine can act as an effective antimicrobial agent," in the mouth and throat, said the study's authors, led by Maria Daglia, a researcher at the University's Department of Pharmaceutical Chemistry. The study was published in the July 11 issue of the Journal of Agricultural and Food Chemistry.

According to the study, apples, tea and mushrooms have been shown in other tests to help kill streptococci. However, "wine also possesses antimicrobial properties" in general, the authors wrote. A prior study found wine to be a potent killer of bacterial strains responsible for some forms of diarrhea.

In order to test if wine could help control streptococci, the scientists isolated eight strains of the bacteria and exposed them to wines purchased from a nearby supermarket. For the red wine, they used a 2003 Valpolicella Classico DOC Superiore and for the white they used a 2003 Pinot Nero DOC. The researchers removed alcohol from the wines--as alcohol is a common ingredient in name-brand oral cleansers--in order to test if other compounds found in wine may exhibit antibacterial behavior.

After preparing the eight strains, the scientists incubated the bacteria to normal body temperature, 98.6 degrees F, then added the wine. The control group, the bacteria that was warmed and left untouched, quickly began to reproduce and flourish. By the end of five hours, the bacterial colonies had grown by an average of 15 percent. (Strep throat symptoms normally appear two to four days after exposure.)

The samples that were treated with 5 ml of wine, on the other hand, not only didn't reproduce, but also began to die. After five hours, the numbers were reduced by up to half. In addition, the red wine proved to be a slightly more effective streptococci killer (though not to a statistically significant degree). The experiments were performed three times, with similar results.

To determine what compounds in wine may be responsible for the observed action, the scientists separated the differing chemical compounds in wine from one another. When they repeated the tests, phenolic compounds, such as tannins and anthocyanidins showed no affect on bacterial growth. However, the organic acids in wine--some found in grapes, some a product of malolactic fermentation--began to kill the bacteria.

As for how much wine people should consume to help prevent streptococci-related ailments, Gabriella Gazzani, the study's coauthor, said that even small amounts of wine may prove to be an effective antimicrobial agent in the mouths of humans. However, further studies were necessary to determine the direct effects of wine on the mouth and throat.

The positive results add to the findings of a previous study found that a red-wine compound may help to destroy two types of bacteria associated with gum disease. In that study, researchers found that the polyphenol resveratrol reduced one type of bacteria by 40 percent and the other by 60 percent, when tested on immune cells from mice. The ability of resveratrol to destroy streptococci was not tested in the Italian study.