Alcohol: your oral microbiota takes a hit!

Alcohol attacks the organism and is a source of cancer. An American team tried to understand the effect of alcohol on the oral flora and its consequences.


More than 700 microorganisms—bacteria, viruses, fungi—make up the oral microbiota. Impairment of this flora is a source of cardiac diseases and cancer. The external factors which contribute to modification of its composition are still not well known. Hence the interest in assessing the impact of alcohol consumption on the bacteria which populate the mouth cavity. The researchers analyzed the oral bacteria of more than 1,000 individuals, taking into account their level of consumption (non-drinker, moderate drinker, heavy drinker) and type of alcohol (spirits, beer, wine).

More ethanol, less lactobacilli

A striking result was observed: there was a reduction in lactobacilli, bacteria that are much used in probiotics and which are beneficial for the oral ecosystem. Ethanol is to blame as it increases the pH of the saliva and blocks its antimicrobial actions. It disrupts the immune functions of the mouth, creates a source of inflammation and promotes bacterial growth, which is strongly associated with cavities. It moreover increases bacterial diversity and fosters the growth of certain species such as Neisseria, capable of synthesizing acetaldehyde, a molecule recognized as carcinogenic by the WHO and usually degraded by lactobacilli. These results suggest the involvement of bacteria and alcohol in the genesis of cancer.

Substances with different effects

Unlike those who drink spirits and beer, wine drinkers differ from non-drinkers in the diversity and profile of their bacteria and display a reduced abundance of several bacterial families. Beer contains a lower concentration of alcohol but has a more complex chemical composition, and could also have an effect on the growth of oral bacteria. Spirits are thought to have an impact close to that of pure ethanol. In other words, not only the quantity but also the type of alcohol can influence the oral flora. A  further step towards understanding the role of bacteria in diseases triggered by alcohol and making new preventive approaches possible.



Fan, X. et al. Drinking alcohol is associated with variation in the human oral microbiome in a large study of American adults. Microbiome 6, (2018).