Drink kills good bacteria, leaving you at the mercy of disease-causing ‘baddies’

Drinking alcohol may do more than just damage the liver; it may tamper with the balance of good and bad bacteria in the mouth. PHOTO | FOTOSEARCH

Drinking alcohol may do more than just damage the liver; it may tamper with the balance of good and bad bacteria in the mouth with far-reaching effects on a drinker’s health, new research published in the journal Microbiome has shown.

Mouths of people who drink one or more alcoholic beverages every day contain excess “bad” (disease-causing) bacteria and smaller amounts of “good” (health-promoting) bacteria, than those of non-drinkers.


This is because drinking kills many good bacteria, leaving space for potentially harmful bacteria to flourish. The bad bacteria then raise the risk of developing gum disease, cavities, cancer and even heart disease.

“Such changes potentially contribute to alcohol-related diseases including periodontal disease, head and neck cancer, and digestive tract cancers,” wrote the research team in their report.

A person’s mouth typically contains 700 types of bacteria, a mix of good and bad. Whereas there is still quite a bit that scientists do not know about the microorganisms in the body (microbiome), they note that one’s lifestyle habits, from the foods you eat, to the medications you take, may influence these bacterial colonies.

Microbiomes are the collection of microorganisms, including bacteria, yeast and viruses, which live in and on the human body, helping digest food, and protect from disease. Good bacteria check the growth of harmful germs, ultimately paving the way to better health.

“Our 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,” said senior investigator and epidemiologist Jiyoung Ahn.


Drinking-related microbiome imbalances were attributed to acids in alcoholic beverages that make the oral environment too hostile for the growth of certain good bacteria.

Another reason could be the build-up of harmful by-products from alcohol’s breakdown, including chemicals called acetaldehydes, which along with the harmful toxins in the mouth from tobacco smoke are produced by bacteria such as Neisseria.

A group of 1,044 healthy adults aged 55 to 87 years, took part in the study. The group consisting of 270 non-drinkers, 614 moderate drinkers and 160 heavy drinkers, provided samples from their mouths for analysis along with detailed information about their eating, drinking and other lifestyle habits.

People who drank more had less abundant populations of Lactobacilli, a family of good bacteria known to promote reduction of gum inflammation.

“Evidence shows that Lactobacilli have a beneficial effect on oral health.

“These findings may lead to better understanding of the role that oral bacteria play in alcohol-related diseases,” the team wrote.

It is not clear, however, if drinking simply kills some bacteria, allowing others to flourish, or whether it encourages the bad bacteria to flourish by affecting saliva production or by creating a friendlier environment for the bad bacteria, the scientists noted.

The team recommended a randomised trial to test the effect of prolonged moderate or heavy drinking or abstinence from drinking on the oral microbiome. They also plan to study how food and drink affects the microbiome.


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