A 40-year-old man was acquitted of a drunken driving offense after doctors confirmed he had a rare condition: auto-brewery syndrome.

One man was charged with drunken driving after crashing his truck and spilling 11,000 salmon onto a highway in Oregon. Another was secretly recorded by his wife, who was convinced he was a closet alcoholic. And in Belgium, a brewery worker was recently pulled over and given a breathalyzer test, which said that his blood alcohol level was more than four times the legal limit for drivers.

The problem? None of those men had been drinking.

Instead, they all were diagnosed with a rare condition known as auto-brewery syndrome, in which a person’s gut ferments carbohydrates into ethanol, effectively brewing alcohol inside the body.

This week, the man in Belgium was acquitted of a drunken driving offense — he wasn’t a boozer, the court found; his body was essentially making its own beer.

It’s the latest turn in the spotlight for the strange disorder, which periodically appears in a flurry of headlines after a particularly odd or egregious case. Most incidents involve accusations of drunken driving, when people who have the disorder, known as A.B.S., get behind the wheel of a car believing they are sober. Reactions to such defenses often range from admiring to dismissive, but medical doctors and science have long backed up that the strange condition does exist.

The condition has been studied in some capacity for more than a century. When a person with the syndrome ingests carbohydrates, fungi in their gastrointestinal tract converts it into ethanol. The process begets all the normal effects of inebriation — lack of coordination, memory loss, aggressive behavior — without the alcohol consumption.

Perhaps most confounding is that the disorder can cause blood-alcohol levels in people that would be lethal if achieved conventionally. One woman, who was pulled over in New York and breathalyzed after having a flat tire, measured 0.40, a level that is considered to be potentially fatal. While many people with the condition do exhibit the more traditional effects of alcohol consumption, others have been known to behave mostly sober, even when tests show they clearly are not.

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