​A new study reveals that drinkers who have one or more alcoholic drinks per day have an overabundance of oral bacteria linked to gum disease, some cancers, and heart disease.

They also have fewer bacteria known to check the growth of other, harmful germs.

The study's authors suggest their study offers clear evidence that drinking is bad for maintaining a healthy balance of microbes in the mouth and could help explain why drinking, like smoking, leads to bacterial changes already tied to cancer and chronic disease.

The team's study may offer evidence that rebalancing some of the 700 types of bacteria in the mouth – or oral microbiome – could potentially reverse or prevent some health problems tied to drinking.

This new report is the first to directly compare drinking levels and their effects on all oral bacteria.

Specifically, drinkers had more of the potentially harmful Bacteroidales, Actinomyces, and Neisseria species, and fewer Lactobacillales, bacteria commonly used in probiotic food supplements meant to prevent sickness.

Researchers note that while their study was large enough to capture differences between bacteria among drinkers and non-drinkers, more people would be needed to assess any microbiome differences among those who consumed only wine, beer, or liquor.

Some 101 wine-only drinkers were involved in the latest study, in addition to 39 who drank only beer and 26 who drank only liquor.

Study senior investigator and epidemiologist Jiyoung AhnAhn says her team's next steps are to work out the biological mechanisms behind alcohol's effects on the oral microbiome. And she emphasized that her work is still a long way from determining if blocking or promoting any particular changes in the microbiome would lead to healthy bacteria levels similar to those found in non-drinkers.

Possible explanations for drinking-related microbiome imbalances, Ahn says, could be that acids in alcoholic beverages make the oral environment hostile for certain bacteria to grow. Another reason, she says, could be the buildup of harmful byproducts from alcohol's breakdown, including chemicals called acetaldehydes, which along with the harmful toxins in the mouth from tobacco smoke, are produced by certain bacteria, such as Neisseria.