Do you know about alcoholic self-fermentation syndrome? Rare and spectacular, it produces the effects of alcohol… without ingesting it. The explanation lies in the gut.
Prosecuted for repeated drunk driving, a 40-year-old Belgian was acquitted in April 2024 after proving that he suffered from alcoholic self-fermentation syndrome. This phenomenon, also known as “intestinal fermentation syndrome” or “auto-brewery syndrome”, is extremely rare. A handful of people in the world are affected, and barely twenty in France. “In these patients, the body produces ethanol when they consume a lot of carbohydrates, such as bread, pasta or potatoes,” explains Dr Joséphine Sérinet, general practitioner at the Alpha Alcoological Center in Royan. This phenomenon can lead to a state of intoxication, with an alcohol level of up to 4 grams per liter of blood (i.e. 8 times the authorized limit on French roads!), without any consumption of alcohol.
This syndrome can have several causes. “These causes are generally linked to factors that disrupt the balance of the intestinal flora or promote the excessive growth of yeast in the digestive system,” continues the doctor. “The balance between different species of bacteria and yeast in the gut is crucial for healthy digestion.” Some types of yeast, such as Candida albicans, ferment sugars in food and produce alcohol. An overgrowth of these yeasts is often the direct cause of self-fermentation syndrome.
Antibiotics disrupt the intestinal microbiota. “Repeated and prolonged consumption of antibiotics destroys the beneficial bacteria that control the growth of yeast, promoting their proliferation and self-fermentation,” emphasizes Dr. Sérinet. Adolescents treated with antibiotics for acne for several months are at risk. Certain intestinal diseases, such as irritable bowel syndrome, Crohn’s disease, ulcerative colitis, or operations such as bypass or sleeve surgery, create an environment favorable to the growth of yeast and fermentation. Metabolic diseases, such as diabetes, increase the concentration of glucose in the intestines, providing additional substrate for yeast fermentation.
The symptoms of alcoholic self-fermentation syndrome are similar to those of inebriation. “Depending on the level of alcohol produced by the body, the person may feel drunk, headaches, nausea and fatigue. Depending on the amount of carbohydrates consumed, they may develop confusion, dizziness and speech impediments.” If the syndrome is not treated, long-term effects such as increased tolerance to alcohol, risk of dependence, cirrhosis, high blood pressure, or neurological damage or hepatitis may appear.
“In all cases, the breathalyzer will be positive,” assures Dr. Sérinet. It can be supplemented by a glucose challenge test. The patient ingests a solution with 200 grams of glucose, and his ethanol level is measured at different time intervals. “In certain cases, a fibroscopy and/or a biopsy may be performed to collect gastrointestinal secretions for bacterial and fungal cultures.”
Treatments aim to restore the balance of the microbiota. “If the syndrome is linked to taking antibiotics, the patient will have to stop the treatment immediately,” warns Dr. Sérinet. For gastrointestinal diseases or diabetes, specific treatment will be offered. Probiotic supplements containing beneficial bacteria can help restore the balance of gut flora and reduce excessive yeast growth. Antifungal medications may be prescribed. A low-carbohydrate diet is often implemented. “Psychological support can be beneficial, particularly if the person needs to go through withdrawal or has chronic alcohol-related disorders.”