Most beer guts are the result of consuming fermented brew, but a new case study describes a rare syndrome that had one man's gut fermenting brew, not consuming it.

It's called gut fermentation syndrome or auto-brewery syndrome, and it's "a relatively unknown phenomenon in Western medicine" according to a study published in July's International Journal of Clinical Medicine. "Only a few cases have been reported in the last three decades" according to Dr. Barbara Cordell, the dean of nursing at Panola College in Carthage, Texas, and Dr. Justin McCarthy, a Lubbock gastroenterologist, the study's authors.

The most current case comes courtesy of an unnamed 61-year-old Texas man who for five years seemed to be drunk -- all of the time.

His wife, a nurse, began to give him breathalyzer tests. Even when he hadn't been drinking at all, his blood alcohol content was as high 0.40 -- five times the legal driving limit -- according to the study.

But the medical community was largely unaware of Gut Fermentation Syndrome then, so the patient wasn't always believed. In 2009 he was admitted into an emergency room on a day he hadn't had a sip of alcohol and blew a 0.37.

"The physicians were not aware of any way that a person could be intoxicated without ingesting alcohol and therefore believed he must be a "closet drinker," the paper says.

Finally, after a 24-hour observation period at a gastroenterology practice in 2010 -- one in which he saw no visitors and underwent a battery of tests -- doctors figured out what was ailing him: His stomach was turning food into booze.

"The underlying mechanism is thought to be an overgrowth of yeast in the gut whereby the yeast ferments carbohydrates into ethanol."

After a regimen of antifungal medication, his yeast was in check, and he was registering zeroes on the breathalyzer.

The authors conclude their paper by imploring their colleagues in the field to take gut fermentation syndrome seriously.

"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 authors write.