Drunk Without Drinking

NAFLD, or nonacoholic fatty liver disease, is common in people with type 2 diabetes, especially when blood glucose levels aren't controlled. More than 50% may develop it.

And of course a high intake of alcohol can produce fatty liver disease.

Now researchers have discovered that more than half of patients with NAFLD have gut bacteria that produce alcohol from the sugar the people eat. There's apparently a specific bacterial strain of  Klebsiella pneumoniae that produces more alcohol than usual, and this strain was found in 61% of people with NAFLD, but only 6% of controls.

Mice fed these strains of K. pneumoniae developed signs of liver damage. When these mice got an antibiotic that killed K. pneumoniae, their condition was reversed.

One man studied had severe liver damage and a condition with the name Autobrewery Syndrome. It's normally caused by alcohol-producing yeast, but this man  had no signs of yeast infection. When tested on an alcohol-free high-carbohydrate diet, he had a very high blood alcohol concentration of 400 mg/L, or .04%. Legal intoxication is usually .08%.

Now, most people wouldn't produce as much alcohol as this man did on a high-carbohydrate diet. But the production of a smaller amount over a long period of time could damage the liver of a person who never drank alcohol.

This is another reason to avoid high carbohydrate diets. The bacteria seem to produce alcohol only when fed a lot of carbohydrates that can be broken down into glucose.

You can read the full study here.

They point out that endogenous alcohol production by particular bacteria is not the only cause of NAFLD: "It would be worth emphasizing that it has become clearer that NAFLD is a very heterogeneous disease and the findings here likely represent just one type of etiology."

But it's a fascinating finding and makes one wonder how many other unanticipated products of gut microbes contribute to disease.