Lovers of red wine, rejoice! Researchers have now identified yet another reason why you should keep on enjoying this beverage.

Some of us love to savor a glass of red wine—or two—with dinner every once in a while.

The catch is that this velvety drink often leaves the teeth stained, so maybe it's not such a good idea to order it on your first date or while out on a business dinner.

That being the case, it's certainly not intuitive to infer that red wine could do anything for your oral health—the contrary, rather.

Still, this is precisely what a study conducted by researchers from Spain suggests.

The research was led by M. Victoria Moreno-Arribas and colleagues from Instituto de Investigación en Ciencias de la Alimentación in Madrid, and the Department of Health and Genomics at the Center for Advanced Research in Public Health in Valencia.

Moreno-Arribas and team have now published their findings in the Journal of Agricultural and Food Chemistry.

Polyphenols to the rescue

We already had plenty of reasons to be partial to a glass of Merlot or Cabernet, even beyond their deep flavors and the way they make even a frugal meal seem richer and more sophisticated.

This drink has actually been found to bring a lot of health benefits. A recent study said that it could help to keep the brain young, and previous research has tied it to hormonal health as well as heart disease prevention.

With so many good qualities, we hardly needed more persuasion to slash any emerging sense of guilt and let the red wine flow.

Yet Moreno-Arribas and her colleagues have revealed another merit that speaks in favor of red wine: some of its components may protect against the formation of cavities and against gum disease.

Many of the health benefits of red wine come from its content of polyphenols, which are a series of micronutrients with antioxidant properties. As antioxidants, they can protect against action of free radicals, which are unstable atoms that play a key role in the cellular aging process.

But polyphenols are nutritional superheroes with many secret weapons, and one of these is their impact on our gut bacteria. Some polyphenols can be absorbed into the small intestine, there to interact with the gut microbiota and fend off some of the bacterial "bad guys" that might threaten our health.

Picking up on this thread, Moreno-Arribas and colleagues hypothesized that polyphenols found in red wine and grapes could have a similar, protective effect in the mouth, fending off harmful oral bacteria that cause cavities and gum disease.

What happens in the mouth

In the new study, the scientists first compared the effect of two types of polyphenol typically found in red wine (caffeic acid and p-coumaric acid) as well as that of red wine and grape seed extracts (Provinols and Vitaflavan) on three harmful oral bacteria: Fusobacterium nucleatum, Streptococcus mutans, and Porphyromonas gingivalis.

What they found—experimenting with a laboratory model of gum tissue—was that the two red wine polyphenols caffeic acid and p-coumaric acid were most effective at repelling the harmful oral bacteria and preventing them from attaching to healthy tissue.

Next, they tested a mix of caffeic acid, p-coumaric acid, and S. dentisani, which is an oral probiotic that, as recent research has suggested, may help to prevent tooth decay.

This experiment was even more successful, as the protective effect of the two polyphenols was enhanced by the presence of the probiotic.

Finally, the analysis of phenolic metabolites, which are substances formed as the polyphenols start transforming in the mouth, suggested that these small products may in fact be the "active ingredient" associated with the polyphenols' protective effect.

So go ahead—pour yourself a glass of red wine tonight, safe in the thought that this drink, at least, won't cause you any oral suffering. Of course, don't overdo it; red wine is an alcoholic beverage, after all, and too much alcohol isn't anyone's friend.

Using a small wine glass, though, could help you curb your appetite a little, so you can delight your palate—and teeth and gums—with some polyphenols, while still keeping your gray matter quite safe.