Drunk Without Drinking": New Study Reveals Gut Microbes Behind Rare Intoxication Syndrome

 

 

In a groundbreaking development, researchers have pinpointed the exact gut bacteria and biological pathways responsible for auto-brewery syndrome (ABS) — a rare disorder where individuals become intoxicated without consuming any alcohol. Known as "drunkenness disease" or gut fermentation syndrome, ABS occurs when certain microbes in the digestive system ferment carbohydrates from food into ethanol (alcohol), which then enters the bloodstream and causes real symptoms of intoxication.

A major study published on January 7, 2026, in Nature Microbiology by scientists from Mass General Brigham and the University of California San Diego analyzed 22 patients with ABS, comparing them to unaffected household members and healthy controls. The findings revealed that patients' gut samples produced significantly more alcohol than those of others. Key culprits include bacterial species such as Escherichia coli and Klebsiella pneumoniae, which convert sugars into ethanol through specific fermentation pathways. During symptom flare-ups, elevated enzymes linked to these processes were observed.. 

“Some people get drunk without drinking because their gut bacteria produce alcohol from food,” explained the researchers. Tests confirmed that ABS patients' microbiomes act like an internal distillery, especially after carb-heavy meals.

This condition, though documented since the 1940s (with earlier hints dating back over a century), has historically been misunderstood and underdiagnosed. Patients often face skepticism from doctors, family, and even legal authorities — some have been falsely accused of secret drinking or charged with drunk driving despite no alcohol intake. Symptoms mimic traditional drunkenness and can include:

Dizziness, slurred speech, and stumbling

Nausea, fatigue, and mood changes

Impaired motor skills and coordination

Brain fog or hangover-like effects

These episodes typically follow consumption of high-carbohydrate or sugary foods (like pasta, bread, sweets, or fruit juice) and can last hours, similar to alcohol intoxication from drinking.

Risk factors include prolonged antibiotic use (which disrupts gut balance), diabetes, liver issues, high-carb diets, or conditions like short bowel syndrome. In one recent case highlighted in the study, a fecal microbiota transplant (transferring healthy gut bacteria) provided long-lasting relief, suggesting promising future treatments.

Diagnosis is challenging and requires ruling out other causes, often involving monitored carbohydrate challenges where patients fast, then consume glucose while blood/breath alcohol levels are tested repeatedly. Treatment typically combines:

Antifungal or antibiotic medications to target overgrown microbes

Probiotics to restore healthy gut flora

Low-carbohydrate, high-protein diet to starve the fermenting organisms

While no universal cure exists yet, many patients achieve symptom control or remission with these approaches. The 2026 research marks a major step forward in understanding and validating ABS, potentially reducing misdiagnosis and stigma.

Experts emphasize that ABS is extremely rare — fewer than 100 well-documented cases exist — but likely underreported due to its bizarre presentation. If you or someone you know experiences unexplained intoxication symptoms after eating, consulting a gastroenterologist for microbiome evaluation is recommended.