Drinking alcohol may boost oral bacteria tied to disease

Last Updated: 2018-04-24

By Marilynn Larkin

NEW YORK (Reuters Health) - Alcohol consumption affects the oral microbiome, potentially increasing pathogenic bacteria linked to alcohol-related diseases, researchers say.

"Dysbiosis of the oral microbiome can lead to local oral disease and potentially to cancers of the head, neck, and digestive tract," note Dr. Jiyoung Ahn of Perlmutter Cancer Center at NYU Langone Health in New York City and colleagues.

"However," they add, "little is known regarding exogenous factors contributing to such microbial imbalance."

The team investigated the impact of one such factor - alcohol consumption - in a cross-sectional study of 1,044 U.S. adults (mean age, 67.7, 95% white) participating in two ongoing cancer trials.

All participants were healthy when they enrolled in the studies and provided mouthwash samples of their oral microbiome, along with information about their alcohol consumption: 25.9% were non-drinkers; 58.8%, moderate drinkers; and 15.3%, heavy drinkers.

Among alcohol drinkers, 13% drank wine only; 5% drank beer only; and 3.4% only drank liquor. The alcohol drinking groups had higher percentages of men and smokers.

The team used various laboratory tests to genetically sort and quantify the oral bacteria according to drinking level, identifying the abundance of specific oral taxa.

As reported online April 24 in Microbiome, the diversity of oral microbiota and overall bacterial profiles differed between heavy drinkers and non-drinkers, and the abundance of commensal order Lactobacillales tended to be decreased with higher alcohol consumption.

Certain genera were enriched in individuals with higher alcohol consumption, including Actinomyces, Leptotrichia, Cardiobacterium, and Neisseria.

Some of these genera contain oral pathogens, according to the authors, while Neisseria can synthesize the human carcinogen acetaldehyde from ethanol.

After controlling for drinking level, the team found that microbial diversity and profiles may differ between non-drinkers and wine drinkers, but not between non-drinkers and liquor or beer drinkers. However, the study was not powered to assess differences among those who consumed only wine, beer or liquor.

After excluding current smokers, all significant differences between drinkers and non-drinkers remained.

"Heavy alcohol drinking is a well established risk factor for multiple diseases, including cancers of the head and neck, esophagus, colon and breast, as well as liver disease and cardiovascular diseases," Dr. Ahn told Reuters Health by email.

"Our study provides another reason to avoid heavy alcohol drinking: to maintain a healthy oral microbiome, which is important to our health," she said.

Dr. Keith Roach, an internist at NewYork-Presbyterian/Weill Cornell Medical Center in New York City told Reuters Health, "As a clinician, I would say the results are certainly plausible. Frequent use of alcohol could certainly affect the microbiome, and the study has examined this meticulously."

"What is less clear is the impact on health, and this study does not address that," he said by email. "There are hints that the overall effect is likely to be potentially harmful - for example, the loss of healthy Lactobacillus species and the relative increase in Neisseria species suggest potential for harm."

"People with excess alcohol use are known to be at higher risk for several cancers," he continued. "It is intriguing that the microbiome may possibly have a role in this, which could conceivably lead to strategies to prevent changing the microbiome with a goal of risk reductions in people who use alcohol."

"Further, some known effects on dental health, which can in turn affect vascular inflammation, could be in part due to microbiome changes," Dr. Roach noted. "However, the evidence is strong that people who use alcohol are at no increased risk for coronary artery disease, even though they are at higher risk for other types of heart disease."

Dr. Lauren Levi, a clinical instructor of Dentistry at the Icahn School of Medicine at Mount Sinai in New York City called the findings "plausible and very interesting."

"The study adds insight into the effect of alcohol consumption on the oral microbiome," she told Reuters Health by email. "However, I think further studies are indicated to more clearly elucidate the relationship between alcohol consumption and oral microbiome dysbiosis, (and) the study highlights the importance of examining this link."

SOURCE: http://bit.ly/2FdptyJ

Microbiome 2018.