This week a Belgian brewery worker was acquitted of drink driving because he suffers from auto-brewery syndrome.

This is a rare and not fully understood condition where the body ferments sugar and starch into significant quantities of ethanol in the gut. Ethanol is the form of alcohol found in beer, wine and spirits.

The accused didn’t present with symptoms of intoxication, despite a higher blood alcohol reading.

This was unusual because people with auto-brewery syndrome generally have symptoms of being drunk. The syndrome is sometimes known as “drunkenness disease”.

Intoxication can occur after drinking a small amount of alcohol.

The fact that the man was a brewery worker was a coincidence, adding to the quirky comedy of the case. Three doctors confirmed the diagnosis.

We’re all home brewers

Tiny but measurable amounts of ethanol are produced in the gut every day as a by-product of digestion. This internal home brew is a normal result of anaerobic degradation of sugars by bacteria and fungi.

It’s harmlessly absorbed by what’s known as portal circulation and removed by the liver.

Auto-brewery syndrome occurs when fermenting yeast or bacteria become pathogenic, causing extreme blood alcohol levels. It’s been diagnosed in men, women and children.

The state of intoxication doesn’t appear to be constant.

In 2015, a New York state school teacher, aged 35, was found to be four times over the blood alcohol limit. Police had pulled her over because she was driving erratically.

She failed breathalyser tests and several field tests (walking in a straight line, touching her nose with her eyes closed) for sobriety.

The woman had the charge of DUI dropped, but it was a close call. The prosecutors tried to have the charges against her re-instated.

The problem is that too many drunk drivers falsely claim to have the syndrome.

As the BBC reported: “Medical and legal experts say the condition, also known as gut fermentation syndrome, is being raised more frequently as a defence in drink-driving cases.”

There are only a few dozen confirmed cases of auto brewery syndrome in the world. But news media love these stories of sufferers getting in trouble with the law. Hence, the word of a ‘get out of jail free’ card for drunk drivers has spread.

In the teacher’s case, her intoxication happened quickly.

How do you get auto-brewery syndrome?

You can’t be born with the syndrome. However, according to Healthline, you may be born with or get another condition that triggers auto brewery syndrome.

For example, in adults, too much yeast in the gut may be caused by Crohn’s disease. This can trigger auto-brewery syndrome.

So can liver problems. In these cases, the liver isn’t able to clear out alcohol fast enough, and even a small amount of alcohol made by gut yeast leads to symptoms.

People with diabetes and obesity are more prone to the condition. (Once diagnosed you’d be advised to avoid foods that are high in carbohydrates and sugar.)

Toddlers and children with a condition called short bowel syndrome have a higher chance of getting auto brewery syndrome. In a 2006 case study, a girl aged three routinely got “drunk” after drinking fruit juice.

Dizziness, headaches and dehydration are among the symptoms, apart from falling over.

Generally, auto brewery syndrome is treated with a change in diet, antibiotics and anti-fungal medication.