woman holding stomach, stomachache, upset tummy
© LaylaBird/E+/Getty ImagesAuto-brewery syndrome is an extremely rare condition in which bacteria and fungus in the gastrointestinal tract turn the carbohydrates in everyday food into ethanol.
Her breath reeked of alcohol. She was dizzy, disoriented and weak, so much so that one day she passed out and hit her head on a kitchen counter while making lunch for her school-age children.

Yet not a drop of liquor had passed her lips, a fact that the 50-year-old Toronto woman and her husband told doctors for two years before someone actually believed her.

"She visited her family doctor again and again and went to the emergency room seven times over two years," said Dr. Rahel Zewude, an infectious disease specialist at the University of Toronto.

Doctors found the woman's alcohol levels could range between 30 millimoles per liter and 62 millimoles per liter — below 2 millimoles per liter is normal, Zewude said.

Alcohol levels of up to 62 millimoles per liter are extraordinarily high and would be considered life-threatening, even fatal, said Barbara Cordell, president of an advocacy association called Auto-Brewery Syndrome Information and Research, which provides patient education and does research on the unusual condition.

While no one she knows has had alcohol levels reach that level, many people can function at blood alcohol levels of up to 30 millimoles per liter or 40 millimoles per liter, Cordell said in an email.

"I know of over 300 people diagnosed with auto-brewery syndrome and we have over 800 patients and caregivers in our private Facebook support group," said Cordell, who was not involved in the new case.

"Part of the mystery of this syndrome is how these people can have these extremely high levels and still be walking around and talking."

All of the emergency room doctors questioned the Toronto woman's drinking habits, and she was examined by three different hospital psychiatrists who concluded that she did not meet criteria for the diagnosis of alcohol use disorder.

"She told doctors her religion does not allow drinking, and her husband verified she did not drink," said Zewude, who treated the woman and coauthored a report on the anonymous case that published Monday in the Canadian Medical Association Journal.

"But it wasn't until the seventh visit that an emergency room doctor finally said, 'I think this sounds like auto-brewery syndrome,' and sent her to a specialist," Zewude said.

Dr. Fahad Malik, a gastroenterologist at United Heath Services in Binghamton, New York, who currently has 30 patients with the disorder, said in an email that being treated with disbelief and ridicule is common for patients. He was not involved in the new case study.

"Most patients have been disregarded as 'closet drinkers' or with behavior conditions prior to diagnosis," said Malik, who is also a clinical assistant instructor at the State University of New York Upstate Medical University.

Extremely rare and frequently unrecognized

Auto-brewery syndrome, also known as gut fermentation syndrome, is an extremely rare condition in which bacteria and fungus in the gastrointestinal tract turn the carbohydrates in everyday food into ethanol. The first known case occurred in 1946 in Africa, when a 5-year-old boy's stomach ruptured for no known reason. An autopsy found his abdomen filled with a "frothy" fluid smelling of alcohol.

Since 1974, 20 diagnosed cases of auto-brewery syndrome have been reported in English medical literature, according to an April 2021 review. Additional reports of auto-brewery symptoms have occurred in Japan, where the condition is known as meitei-sho, or "alcohol auto-intoxication syndrome."

Auto brewery syndrome occurs when certain species of bacteria and fungi overpopulate a person's gut microbiome, basically turning the gastrointestinal tract into a still apparatus.

Scientists believe the process takes place in the small bowel and is vastly different from the normal gut fermentation in the large bowel that gives our bodies energy.

While a number of pathogens can contribute, most cases are due to an overgrowth of two species of fungi: Saccharomyces and Candida. Candida lives on the body and in the mouth, digestive tract and vagina, often taking over when more beneficial bacteria are killed off by a round or two of antibiotics.

A July 2013 report documented the case of a 61-year-old man who had frequent bouts of unexplained drunkenness for years before being diagnosed with an intestinal overabundance of Saccharomyces cerevisiae, or brewer's yeast, the same yeast used to make beer.

Many people with the syndrome can function with an enormous amount of metabolically generated alcohol in their system, sometimes only realizing it when they get in trouble with the law.

A North Carolina man in his late 40s was pulled over for what cops were convinced was drunk driving. He denied drinking despite a blood alcohol level of 0.2%, the equivalent of consuming 10 drinks an hour and about 2.5 times the legal limit.

"It's not as rare as we think, it's (just) rarely diagnosed," Cordell said. "I believe many people may walk around feeling foggy and just think they are tired when they might be fermenting alcohol."

'A metabolic storm'

There are risk factors for auto-brewery syndrome. Diabetes and liver disease can play a role as can gastrointestinal diseases such as inflammatory bowel disease and short gut syndrome, in which the small intestine is damaged or shortened, Zewude said. There may even be a genetic predisposition connected to how well a person metabolizes alcohol.

"But all of these things have to collide at the perfect time," she said. "It requires multiple risk factors interacting and creating a metabolic storm for this syndrome to emerge in an individual."

For Zewude's Toronto patient, that metabolic storm began in her mid 40s when she started to have concurrent urinary tract infections, each treated with a round of antibiotics. Beneficial bacteria in her intestinal tract began to die off, allowing the fungi lying in wait to take over.

That much yeast needs fuel, which it gets from carbohydrates in the diet. By the time the woman was 48, her body was turning nearly every carb she ate into alcohol.

"If she didn't eat many carbs, the symptoms weren't so bad," Zewude said. "But then she might have a slice of cake or another big carbohydrate meal, which led to a rapid rise in her alcohol level. These were the times where she might be getting lunch ready for her kids and just fall asleep."

Treatment for auto-brewery syndrome begins with a course of fungicides prescribed after a biopsy or colonoscopy identifies the specific pathogens that have colonized the gut, Zewude said. Starting with a broad spectrum fungicide can backfire.

"Antimicrobial resistance is an important part of the syndrome, because part of the reason people get this is because of the frequent antibiotic use that disrupts their gut," she said. "You need to start narrowly, and then if the patient becomes resistant to that fungicide, try others."

In addition to killing off the yeast, patients are expected to follow an extremely restricted low-carb diet. "No carbs would be best, but it's almost impossible to do that," Zewude said. Probiotics to build back beneficial bacteria can also help, she said.

Today, the woman is no longer taking antifungal medications, but she remains on a very low-carb diet after having a relapse. As each person's experience is different, it's important that patients stay in close touch with their doctors to manage their condition, Zewude said.

"In this case, the woman has a very supportive husband, who called me immediately when he began to smell alcohol on her breath again," Zewude said. "For anyone dealing with the syndrome, it's important that your spouse, friend, roommate or whatever, know the signs and symptoms and connect with physicians or bring the person to the emergency department when this occurs."