Auto-brewery syndrome is a condition in which yeast trapped in the digestive system can cause alcohol to ferment in the human stomach. After eating carbohydrates, such as bread or pasta, the sugar in the food mixes with the yeast and produces ethanol, causing intoxication. While it might sound like the most awesome disease ever, the implications are actually quite dangerous.
In 2013, Barbara Cordell, dean of nursing at Panola College and Dr. Justin McCarthy, a gastroenterologist, published a paper in the International Journal of Clinical Medicine, detailing a bizarre case in which a 61-year-old Texas man visited an emergency room, clearly intoxicated. A breathalyzer test showed he had a blood alcohol reading of 0.37 percent, enough to kill a person. The attending staff, of course, believed that he’d overindulged. However, the man was adamant that he’d had nothing to drink. Doctors still believed that he had been guzzling liquor. But the case intrigued Dr. McCarthy, and he sequestered the patient in a room with no access to alcohol. Bizarrely enough, he continued to get even more drunk after only eating solid food.
After some testing, they learned that the man’s digestive system was crawling with Saccharomyces cerevisiae, brewer’s yeast. Whenever he ate something starchy, such as a bagel, a simple chemical reaction occurred in his belly. The yeast devoured the sugars, leaving ethanol as a waste product and rendering the man instantly drunk, brewing a strong alcohol right inside his belly.
It is normal for the human body to produce tiny amounts of alcohol called “endogenous ethanol” through various processes, but the concentration is so insignificant, you’d never notice it. However, the man in question had a blood alcohol level nearly five times the legal limit for driving a car.
Auto-brewery syndrome was not unknown, but it had only previously been described in Japan, where it is called “meitei-sho.” Again, it was a startlingly rare condition, but there are people who possess a mutation in their liver enzymes which does not allow them to properly process alcohol, likely promoting the condition. Other contributing factors are thought to be the heavy consumption of carb-rich food like rice, gastrointestinal surgery, and taking antibiotics, which can wipe out the bacteria in the stomach and make room for infestations of yeast.
While free beer seems like the best side effect to the coolest medical condition of all time, there are several scary factors at play. Had the man been just slightly drunker, he likely would have died from alcohol poisoning. And he could have easily been involved in an accident after doing something no more innocuous than eating breakfast. The man was treated with antifungal medication and a low-carbohydrate diet, and his symptoms thankfully cleared up.