A Texas man in his 60s who would become drunk without touching a drop of alcohol turns out to have had a beer gut — his gut was brewing beer.

The unusual case study of Gut Fermentation Syndrome, a relatively unknown phenomenon also known as Auto-Brewery, was published in the International Journal of Clinical Medicine.

Authors Barbara Cordell and Dr. Justin McCarthy detail how the man spent five years becoming unexplainably drunk before experts realized the cause was too much brewer’s yeast in his gut. A carbohydrate-rich diet caused an overgrowth of yeast, which would ferment the sugars into ethanol and make him drunk.

“It would behoove health-care providers to listen more carefully to the intoxicated patient who denies ingesting alcohol,” write Cordell, the dean of nursing at Panola College in Texas, and McCarthy, a gastroenterologist in Texas.

“This is a rare syndrome but should be recognized because of the social implications such as loss of job, relationship difficulties, stigma, and even possible arrest and incarceration.”

The bouts of unexplained drunkenness started in 2004 after the man underwent surgery for a broken foot and was treated with antibiotics, which may have affected his gut bacteria. He would become extremely drunk after just two beers, and seemed intoxicated even when he had not been drinking.

In an interview with NPR, Cordell said, “He would get drunk out of the blue – on a Sunday morning after being at church, or really, just anytime.”

The man’s wife, a nurse, used a breathalyzer and began noting his blood-alcohol concentration, which often reached between 0.33 and 0.44. (By comparison, the legal limit for drivers in Canada and the United States is 0.08.)

Over the years, the episodes became more frequent and severe and in November 2009 the man stumbled into an emergency room. That day, he had not touched any booze, but his blood-alcohol concentration was 0.37. He was treated for severe alcohol intoxication and doctors suspected he was a closet drinker.

The following January, the then-61-year-old, underwent a complete gastroenterology workup. Three months later he was admitted to hospital for 24-hour observation — after his belongings were checked to make sure he wasn’t smuggling in alcohol.

During that 24-hour period, no visitors were allowed. Experts fed him high-carbohydrate foods and snacks, while monitoring his blood-alcohol concentration, which at one point was 0.12. Tests revealed he had been infected with Saccharomyces cerevisiae, also known as brewer’s yeast.

For six weeks, the man was treated with anti-fungals to get rid of the yeast, and placed on a strict diet of no sugars, carbohydrates or alcohol. Throughout treatment, his blood concentration was 0.00 and his gut returned to normal.

In the last three decades, there have only been a handful of similar cases reported, two of them involving children, aged 13 and 3.