New Study Reveals True Cause of Auto-Brewery Syndrome Intoxication

Scientists from four countries have identified the gut bacteria responsible for auto-brewery syndrome, a rare condition in which the human body produces enough ethanol to cause symptoms of intoxication, according to research reported by N+1 citing a study published in Nature Microbiology.

Alcohol Production Without Drinking

Auto-brewery syndrome occurs when ethanol is produced inside the intestines as a result of microbial fermentation. Until now, the condition was widely believed to be caused primarily by brewer's yeast present in the gut microbiota.

To test this assumption, researchers conducted an in-depth study involving 22 patients diagnosed with auto-brewery syndrome and 21 healthy individuals living in the same households. The team performed microbiological, metabolic, and metagenomic analyses of stool samples from all participants.

Unexpected Bacterial Culprits

The results showed that the main producers of alcohol during disease flare-ups were not fungi, but bacteria — specifically Escherichia coli and Klebsiella pneumoniae. During periods of exacerbation, these bacteria generated ethanol in quantities sufficient to induce clinical intoxication.

This finding challenges long-standing assumptions about the syndrome and highlights the role of bacterial metabolism in alcohol production within the human gut.

Fecal Transplant Shows Promising Results

In one notable case, a patient underwent several fecal microbiota transplants using material from a healthy donor.

Following the procedures, the patient entered stable remission and has remained symptom-free for more than 16 months.

According to the researchers, this outcome suggests that restoring a healthy balance of gut bacteria may be an effective treatment strategy for auto-brewery syndrome in certain cases.

Implications for Diagnosis and Treatment

The discovery opens the door to new diagnostic approaches and targeted therapies that focus on bacterial composition rather than antifungal treatment alone. Scientists believe the findings could lead to more accurate identification of the condition and improved long-term outcomes for patients.