Auto-brewery syndrome or gut fermentation syndrome is a condition in which ethanol is produced through endogenous fermentation by fungi or bacteria in the gastrointestinal (GI) system. Patients with auto-brewery syndrome present with many of the signs and symptoms of alcohol intoxication while denying an intake of alcohol and often report a high-sugar, high-carbohydrate diet.
The production of endogenous ethanol occurs in minute quantities as part of normal digestion, but when fermenting yeast or bacteria become pathogenic, extreme blood alcohol levels may result. Auto-brewery syndrome is more prevalent in patients with co-morbidities such as diabetes, obesity, and Crohn disease  but can occur in otherwise healthy individuals. Several strains of fermenting yeasts and rare bacteria are identified as the pathogens. While auto-brewery syndrome is rarely diagnosed, it is probably underdiagnosed.
Various yeasts from the Candida and Saccharomyces families are commensals turned pathogenic that cause auto-brewery syndrome. Two strains of bacteria are also known to ferment ethanol.
Auto-brewery syndrome is a rare condition. The disease has been identified in both male and female adults and children in many countries and is likely underdiagnosed.
A perturbation of the gut microbiome is the underlying condition that allows fermenting microbes to over-colonize. Such gut disturbances are caused by a diet high in carbohydrates and refined foods and the overuse of antibiotic and non-antibiotic drugs in food and medicine.
Other underlying conditions may contribute to the pathogenesis of auto-brewery syndrome:
Auto-brewery syndrome has significant effects on a person’s life. The patient may experience side effects of vomiting, belching, chronic fatigue syndrome, dizziness, loss of coordination, disorientation, veisalgia, and irritable bowel symptoms. Chronic fatigue syndrome can result in health problems such as anxiety, depression, and poor productivity.
Because of the production of significant alcohol levels, people can test over the legal driving limit without consuming any alcohol. The randomness of intoxication episodes can result in difficulties for the patient, including injuries from falls, legal difficulties following driving citations, and strain on social relationships.
The obscurity of the condition challenges practitioners to diagnose and find a successful treatment. A comprehensive history and physical is essential, including a detailed diet history. Family members should supplement the intake history since patients may not remember their episodes of intoxication or what they ate prior to an episode.
Patients may not initially present with signs and symptoms of intoxication but may report neurological symptoms, loss of coordination, and mood changes. Auto-brewery syndrome should be considered in any patient presenting with an elevated blood alcohol level who denies ingestion of alcohol, including those arrested for DWI.
Auto-brewery syndrome is more likely in a patient with chronic intestinal obstruction, gastroparesis, diabetes, or liver dysfunction such as non-alcoholic fatty liver disease (NAFLD) or nonalcoholic steatohepatitis (NASH). An interprofessional approach that includes a psychiatric evaluation should be employed. Auto-brewery syndrome should also be included in the differential diagnosis for D-lactic acidosis.
Evaluation should include:
A coordinated treatment program should include patient input for compliance.
The risk of relapse of auto-brewery syndrome is lessened by avoiding carbohydrates. A nutritionist should be involved in the treatment and management of the disease.
Anything that causes an imbalance between harmful and beneficial bacteria can potentially increase fermentation in the gut. Antibiotics should be avoided if possible. If a course of antibiotics is required, a plan should be in place to again test for fermenting pathogens and treat if necessary.
In single and various combinations, dietary carbohydrate control, antifungal or antibiotic therapy, general antibiotic avoidance, and probiotics have all been reported as successful treatments.
Rule out other possible causes such as head injury, psychiatric disorder, and hidden drinking.
Auto-brewery syndrome should be considered in the differential diagnosis of patients that are not consuming alcohol and yet exhibit the signs and symptoms of alcohol consumption; particularly if they are also consuming a high carbohydrate diet.
Some patients can resolve symptoms of auto-brewery syndrome by stopping antibiotics and following a sugar-free diet. Others may require antifungals or antibiotics, along with diet modification. Probiotics, a low carbohydrate diet, and avoidance of antibiotics may help prevent relapse.
Auto-brewery syndrome is known to have a profound effect on patients and families. Most patients can resume a normal diet and lifestyle after one treatment. Other patients may relapse one or more times, especially if treated with antibiotics that disturb the gut microbiome.
In many cases, auto-brewery syndrome is mistaken for alcohol consumption, creating social and legal issues. Even after symptoms have resolved, the long-term exposure to endogenous ethanol can result in addiction to and cravings for alcohol with subsequent drinking.
Some combination of diet modification, drug therapy, and probiotics usually eliminates symptoms. Patients and healthcare providers should be aware of the possibility of relapse of symptoms. Occasionally a patient cultures an additional yeast that was resistant to the initial drug therapy. Some patients may also require an alcohol treatment program.
Consult gastroenterology, infectious disease, and a registered nutritionist.
Patients should avoid sugars and carbohydrates and eat a diet higher in proteins during treatment. Long-term, patients should be educated on how to maintain a low carbohydrate diet, avoid dietary antibiotics, and abstain from drinking alcohol.
Patients should be taught about the microbiome and to avoid taking antibiotics unless necessary. If given antibiotics, they should ask their provider for a plan to prevent relapse.
Patients should be educated about the possibility of alcohol addiction after symptoms are resolved and be given referrals for alcohol treatment if needed.
Any patient with an elevated blood alcohol level who denies alcohol ingestion should be treated with empathy and compassion by all team members.
The diagnosis and management of auto-brewery syndrome (gut fermentation syndrome) are best done with an interprofessional team that includes a primary provider, a gastroenterologist, an infectious disease specialist, a nurse, and a nutritionist. An endocrinologist should be involved if the patient has diabetes and a hepatologist should be consulted in the event liver complications are detected. Pharmacists review medical treatments, check for drug-drug interactions, and provide patient education. Gastroenterology nurse specialists provide patient and family education, monitor patient progress, and report back to the team.
After diagnosis and stabilization, most patients can be treated as an outpatient. The main goal is to promote patient compliance with dietary changes, supplements, and if needed, medication. As symptoms subside, the healthcare team should assess alcohol cravings and make appropriate referrals.
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