Gut microbes can get you drunk and damage your liver

Gut microbes can get you drunk and damage your liver

Bill Sullivan    Associated Press

(THE CONVERSATION) Imagine that you’re a police officer. You spot a car ahead that is swerving all over the road. You pull the driver over and she’s clearly intoxicated. With slurred speech, she swears that she hasn’t had a drop of alcohol all day. Would you believe her?

In 2016, a woman who had a blood alcohol level four times the legal limit was acquitted of her DUI charge after it was discovered that she had an extremely rare condition called “auto-brewery syndrome.” People with this syndrome carry microbes in their intestines that produce abnormally high levels of alcohol, which they produce when they break down sugars and carbohydrates.

While auto-brewery syndrome is an extreme example, it makes one wonder: Could intestinal microbes be influencing other health or behavioral traits? Jing Yuan at the Capital Institute of Pediatrics in Beijing published a new study in Cell Metabolism showing that an intestinal microbe may cause fatty liver disease by producing high levels of alcohol.

I am a microbiologist and am intrigued by the roles intestinal microbes - known collectively as the microbiome – play in human health. As the author of the book, “Pleased to Meet Me: Genes, Germs, and the Curious Forces That Make Us Who We Are,” I have done extensive research into how our microbiome affects our health, moods and behavior.

Diseased liver, without drinking

The accumulation of excess fats in the liver can cause serious health problems, including inflammation, which can lead to cirrhosis (scarring) and liver cancer. Most people associate fatty liver disease with alcoholism; however, nonalcoholic fatty liver disease, which affects a surprising 80 to 100 million Americans, arises without excessive alcohol intake.

There appear to be multiple causes of NAFLD such as obesity, insulin resistance, high cholesterol or hepatitis C infection. Now Yuan and her colleagues may have identified another.

The discovery occurred when physicians identified a patient who was suffering from both auto-brewery syndrome and severe NAFLD. When researchers examined stool samples from the patient, they found a species of bacteria called Klebsiella pneumoniae. This particular strain of K. pneumoniae was making between four and six times the quantity of alcohol that strains of the same bacteria make in healthy people. This prompted Yuan and her team to examine a cohort of 43 other patients with NAFLD. They discovered that 61% of them possessed K. pneumoniae excreting unusually high amounts of alcohol. Among 48 healthy people, only 6% contained such bacteria.

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