00:57 - Source: CNN
Why we're more bacteria than human

Story highlights

Drinkers' mouths have more bad bacteria that potentially cause disease, one study finds

An increased risk of PMS is linked to drinking alcohol, another study finds

CNN —  

Your mouth naturally contains about 700 types of bacteria, some good but others not so much. The mouths of people who routinely drank one or more alcoholic beverages each day contained an overabundance of bad bacteria and a smaller amount of good bacteria than those of nondrinkers, new research has found.

Having too many harmful mouth bacteria is known to lead to gum disease, heart problems and even some cancers. By contrast, good microbes in our mouths check the growth of harmful germs, ultimately paving the way to better health.

The science journal Microbiome published the new study Monday.

“This is the first comprehensive study of alcohol intake on oral microbiome,” said Jiyoung Ahn, the study’s senior investigator and an epidemiologist at the NYU School of Medicine. “Oral microbiome” is the medical term for the colony of bacteria in our mouths.

Having recently shown that the types of bacteria found in the mouth can influence the development of oral and upper digestive tract cancers, Ahn and her colleagues decided to investigate what diet and lifestyle factors might shape the oral microbiome.

Spit test

A group of 1,044 healthy people between the ages of 55 and 87, most of them white, took part in the study. Overall, the group included 270 nondrinkers, 614 moderate drinkers and 160 heavy drinkers. All of the participants provided spit samples along with detailed information about their eating, drinking and other lifestyle habits.

Ahn and her co-researchers ran laboratory tests to genetically sort and quantify the oral bacteria contained in each person’s sample. The team plotted the results on graphs to better see which bacteria stood out among the drinkers in comparison with nondrinkers.

What did they see? The drinkers had more Bacteroidales, Actinomyces and Neisseria species of bacteria, all potentially harmful, with some causing periodontal disease and others causing a decrease in beneficial bacteria. Compared with nondrinkers, participants who regularly enjoyed a cocktail or two also had fewer Lactobacillales, a family of bacteria known to promote reduction of gum inflammation.

“We did not find a specific threshold level,” Ahn said, though heavier drinking led to more extensive changes in the oral microbiome. She added in an email that “heavy alcohol intake is a known risk factor for multiple chronic diseases, including cancers (head and neck, esophagus, colon and breast), liver disease and cardiovascular diseases.”

More study participants would be needed to understand whether there were any differences between the drinkers who stuck to just one beverage (only beer, say), the researchers note.

And, while many mouthwash brands contain alcohol – they can range anywhere from 10% to 20% alcohol – the new research “studied the effect of alcohol drinking, but did not specifically test the effect of mouthwash,” said Ahn.

Possible explanations for drinking-related microbiome imbalances, Ahn said, could be that acids in alcoholic beverages make the oral environment hostile for certain bacteria to grow. Another reason could be the buildup of harmful byproducts from alcohol’s breakdown.

Drinking or poor hygiene?

What’s “new” here, said Olivier George, an associate professor in the department of neurology at the Scripps Research Institute, is that the researchers conducted a “very comprehensive analysis” of mouth bacteria and that this “could indicate (or not) if there is a level of drinking that doesn’t affect your mouth microbiome.”

That said, it’s “impossible to say if these effects are due to drinking per se or due to the poor hygiene associated with drinking,” said George, who studies addiction but was not involved in the new research.

There’s “tremendous interest” in the role played by bacteria in our body, he said. “They could affect aging, cancer, a variety of health conditions and even control brain function and play a role in behaviors.” However, the study results do not make it clear whether the mouth bacteria imbalance for drinkers influences the development of cancer, he said.

Going forward, Ahn and her colleagues plan to investigate the reasons why drinking alcoholic beverages is associated with a change in the oral microbiome.

In a separate study, researchers say that about one in 10 cases of premenstrual syndrome (PMS) may be linked to drinking. The new research was published Monday in the online medical journal BMJ Open.

’Altering the level of hormones’

Premenstrual syndrome includes any or all of mood swings, tender breasts, food cravings, fatigue, irritability and depression.