The man with a brewery in his gut

by | Gastrointestinal Health, Mental Health, Seniors Health

gut health and beer guts

Sometimes there are cases that completely flummox the medical establishment. So it was in the case of a healthy, 46-year-old man who sought treatment for sudden memory loss, mental changes and episodes of depression that had occurred over a six year period, beginning in 2011. The only notable thing about that year for the man, medically, was that he’d been on a prolonged course of antibiotics for a serious injury to his thumb.

The brain fog and aggressive behaviour he developed after this antibiotic treatment were completely out of character and doctors initially treated him with antidepressants to little effect. One morning, he was pulled over by police, who found his blood alcohol concentration was way over the limit. The weird thing was, he hadn’t been drinking, not that the police believed him. No-one at the hospital believed him either.

It was only when he heard about a similar case – someone who was drunk without consuming alcohol – that he began to suspect what was going on. He had his stool sampled, and the doctors found Saccharomyces cerevisiae, a species of yeast which is more commonly known as brewer’s yeast and is used in the process of making beer. They also tested what happened when the man ate a meal full of carbohydrates: hours later, he had an elevated blood alcohol concentration.

Sudden changes in personality, brain fog, drowsiness and confusion were eventually linked to the alcohol that a man was producing in his gut whenever he ate carbohydrates.

The man was diagnosed with ‘auto-brewery syndrome’ – a rare condition where the gut is colonised with brewer’s yeast which turns carbohydrates into alcohol, getting the person drunk. The treatment was anti-fungal therapy and the man eventually made a full recovery, returning to his normal life.


The authors of this case study say auto-brewery syndrome is probably underdiagnosed. In other words more people may have it than we think. When it comes to unexplained changes in personality and behaviour, ABS might be something to consider if other, more common conditions don’t explain things.