Study: Drinking alcohol ‘reprograms’ gut microbiome, but these changes aren’t key factor in liver damage

Having the occasional night out for drinks may be OK, but drinking heavily everyday is a lot for the human body to maintain. That’s especially the case when it comes to gut health — yet scientists have been at odds over how alcohol affects gut bacteria. A new animal study from researchers at the University of California San Diego, may clear up some of the debate. Their research shows that liver-produced acetate in the gut “reprograms” the microbiome, but these changes don’t impact the liver in the way one might expect.

“You can think of this a bit like dumping fertilizer on a garden,” says Karsten Zengler, PhD, a professor at UC San Diego School of Medicine and study coauthor in a statement. “The result is an explosion of imbalanced biological growth, benefitting some species but not others.”

Most alcohol absorption mainly occurs in the mouth and stomach. It is much rarer for alcohol to reach the intestines, scientists say. While too much booze can lead to this “explosion” of bacteria, they don’t believe the imbalance is the driving factor behind alcoholic liver disease.

For the study, researchers gave mice a molecule that was later broken down in the gut into three acetates. The researchers observed what happened to their gut microbiomes when given additional acetate.

The decision to use acetate—a nutrient used in metabolism, energy expenditure, immune response, and appetite control—is because at certain levels it can hurt or harm your health. At moderate levels, acetate helps with heart health by promoting red blood cell production and memory function. But an excess amount can alter your metabolism and high acetate levels have been linked to a number of diseases, including cancer.

They found the guts of mice reacted the same way to acetate as they would towards alcohol. However, unlike alcohol, the extra acetate did not harm their livers.

“Chronic alcohol consumption is associated with lower intestinal expression of antimicrobial molecules. Persons with alcohol-related liver disease commonly have bacterial overgrowth in their guts,” explains Dr. Zengler. “These findings suggest that microbial ethanol metabolism does not contribute significantly to gut microbiome dysbiosis (imbalance) and that the microbiome altered by acetate does not play a major role in liver damage.”

While the study authors note that the study’s findings won’t lead to any new treatments for alcohol liver disease, it may help in understanding the effect acetate has on the microbiome. What’s more, the findings move the impact of acetate from the theoretical stage where “changes in the gut microbiome are related to ethanol consumption per se are critical…and towards identifying bacteria that are causal for deleterious effects of alcohol consumption, rather than side-effects either of consumption or disease.”

The study is published in the journal Nature Communications.

Leave a Comment