Foods That Turn to Alcohol in the Body: What is Auto-Brewery Syndrome?

October 23, 2025 •

4 min read

While the vast majority of people can eat carbohydrates without worry, a small number of individuals possess a rare and often misunderstood condition known as auto-brewery syndrome, where certain foods turn to alcohol in the body. This unusual disorder causes intoxicating amounts of ethanol to be produced internally, leading to symptoms of drunkenness without consuming alcoholic beverages.

Quick Summary

Auto-brewery syndrome is a rare condition where the gut's microbes ferment carbohydrates and sugars into intoxicating ethanol. This endogenous alcohol production can cause symptoms of drunkenness, fatigue, and cognitive issues. The condition is often linked to an overgrowth of yeast or specific bacteria, poor diet, and prior antibiotic use. Dietary and antifungal interventions can help manage this phenomenon.

Key Points

Auto-Brewery Syndrome Explained: Auto-brewery syndrome (ABS) is a rare medical condition where the gastrointestinal tract ferments ingested carbohydrates into intoxicating ethanol, causing symptoms of drunkenness.
High-Carbohydrate Foods Are Culprits: The foods that turn to alcohol in the body for ABS patients are high in simple sugars and starches, including refined grains, pastries, and sweet fruit juices, which act as fuel for fermenting microbes.
Yeast and Bacteria Overgrowth: The condition is caused by an imbalance in the gut microbiome, often involving an overgrowth of yeast, such as Candida albicans or Saccharomyces cerevisiae, or specific bacteria.
Low-Carbohydrate Diet Is Key: Dietary management involves a strict, low-carbohydrate and low-sugar diet to starve the fermenting organisms and prevent ethanol production.
Medical Intervention is Necessary: Treatment often includes antifungal or antibiotic medications to eliminate the microbial overgrowth, and a probiotic regimen to restore a healthy gut balance.
Symptoms Can Mimic Alcoholism: ABS symptoms include brain fog, slurred speech, and coordination issues, which can lead to social, legal, and medical misunderstandings.
Diagnostic Testing Exists: Diagnosis can be confirmed with a glucose challenge test, which measures blood or breath alcohol levels after consuming a glucose solution.

Understanding Auto-Brewery Syndrome

Auto-brewery syndrome (ABS), also known as gut fermentation syndrome, is a fascinating and often debilitating medical condition. It occurs when a person's gastrointestinal tract, or sometimes the urinary system, creates intoxicating quantities of ethanol from the fermentation of carbohydrates and sugars. This happens due to an imbalance in the gut microbiome, where excessive amounts of fermenting organisms like yeast (e.g., Saccharomyces cerevisiae, Candida albicans) or certain bacteria (e.g., Klebsiella pneumoniae) take over.

The Science Behind Internal Fermentation

The process is similar to how beer or wine is made. In a healthy gut, microbes are in a balanced state and help with digestion. However, in individuals with ABS, the fermenting organisms proliferate and begin to ferment undigested carbohydrates and sugars. This process produces ethanol as a byproduct, which is then absorbed into the bloodstream, causing a rise in blood alcohol content (BAC). The severity of the symptoms varies depending on the amount of fermentable material consumed and the extent of the microbial overgrowth. This can lead to episodes of unexplained intoxication, brain fog, and coordination issues, causing significant medical and social consequences for the affected individual.

Key Food Culprits in Auto-Brewery Syndrome

If you have ABS, the foods that turn to alcohol in the body are primarily those high in simple carbohydrates and sugars, as they provide the fuel for the fermenting microbes. While the severity can vary, eliminating or drastically reducing these items is a core component of management.

High-Carbohydrate and Sugary Foods to Avoid

Simple Sugars: Refined sugars such as sucrose, glucose, and high-fructose corn syrup are a major source of fuel for the fermenting yeast and bacteria. This includes candies, pastries, sugary sodas, and sweetened fruit juices.
Refined Grains and Starches: Items made from white flour, white rice, and potatoes can be particularly problematic. These high-glycemic carbohydrates break down quickly into simple sugars, feeding the microbial overgrowth.
Yeast-Based Products: Fermented foods and yeast-containing products can add to the problem. While often beneficial for healthy guts, yeast-rich items like standard bread, some cheeses, and other fermented products should be avoided during treatment.
Fruits and Juices: Overly ripe fruits, especially those high in sugar like bananas and grapes, naturally contain some alcohol from fermentation. In individuals with ABS, the extra sugar can contribute to endogenous ethanol production. High-fructose fruit juices are also a source of simple sugars.

Comparison: Standard Digestion vs. Endogenous Fermentation

To highlight the difference, here is a comparison of how the body processes carbohydrates in a healthy individual versus someone with auto-brewery syndrome.


Process Feature	Healthy Gut Function	Auto-Brewery Syndrome
Carbohydrate Processing	Digested and absorbed into glucose for energy in the small intestine.	Fermented into ethanol by opportunistic microbes in the gut.
Primary Outcome	Energy production for the body's cells.	Intoxication and related symptoms (fatigue, brain fog).
Microbial Balance	Healthy and diverse microbiome keeps fermenting organisms in check.	Dysbiosis, with an overgrowth of yeast or specific bacteria.
Dietary Impact	High-carb diet provides energy without systemic intoxication.	High-carb diet exacerbates symptoms by providing fuel for fermentation.
Blood Alcohol Level	Minimal to no rise in BAC after eating.	Unexplained and potentially high BAC levels after eating.

Treatment and Management

Managing auto-brewery syndrome involves a multi-pronged approach, focusing on controlling the gut microbiome and restricting the foods that turn to alcohol in the body.

Medical Interventions

Antifungal or Antibiotic Therapy: Prescribed medications target the specific yeast or bacteria causing the overgrowth. Common antifungals include fluconazole or nystatin.
Probiotics: After clearing the overgrowth, a multi-strain probiotic can be used to repopulate the gut with beneficial bacteria and restore a healthy microbiome balance.
Addressing Underlying Conditions: Issues like diabetes, liver disease, or certain gastrointestinal conditions can predispose individuals to ABS. Treating these underlying problems is crucial for long-term management.

Dietary Management

A strict low-carbohydrate, low-sugar diet is a cornerstone of ABS treatment. This starves the fermenting microbes, helping to reduce ethanol production. A nutritionist or other healthcare professional can provide guidance on a diet that is high in protein and healthy fats while eliminating refined carbohydrates, sugars, and yeast-based products.

The Broader Impact and Conclusion

The internal fermentation of foods can have profound medical, social, and legal consequences for those affected. The episodes of unexplained intoxication can lead to dangerous situations, strained relationships, and wrongful legal accusations, particularly concerning driving under the influence. A proper diagnosis, often involving a glucose challenge test to measure internal ethanol production, is vital for confirming the condition. By understanding what foods turn to alcohol in the body for individuals with ABS and adhering to the necessary dietary and medical treatments, patients can regain control of their health and their lives.

While ABS remains a rare condition, its existence highlights the critical role of the gut microbiome in overall health and metabolism. The research into this syndrome is ongoing, with new cases and potential treatments emerging, making awareness among both the medical community and the public crucial for accurate diagnosis and effective management. For more information on gut health and its impact on the body, the National Center for Biotechnology Information (NCBI) offers extensive resources.

Frequently Asked Questions

Auto-brewery syndrome (ABS), also known as gut fermentation syndrome, is a rare condition where bacteria or yeast in your gut produce intoxicating amounts of ethanol from ingested carbohydrates and sugars, leading to symptoms of alcohol intoxication without drinking alcohol.

Individuals with auto-brewery syndrome should avoid high-carbohydrate foods and simple sugars. This includes refined carbohydrates like white bread, pasta, and rice, as well as sugary foods, beverages, and juices. A low-carb, high-protein diet is often recommended.

Yes, while generally healthy, fermented foods like kombucha, sauerkraut, and kefir contain beneficial bacteria and yeast that can exacerbate the microbial imbalance in someone with auto-brewery syndrome and should be avoided, especially during initial treatment.

Yes, prolonged or frequent use of antibiotics can disrupt the natural balance of the gut microbiome. This can lead to an overgrowth of alcohol-producing yeast and bacteria, which is a significant contributing factor to ABS.

Diagnosis typically involves a doctor noting symptoms of intoxication despite denied alcohol consumption. A confirmatory test is the glucose challenge test, where blood or breath alcohol levels are measured after a glucose solution is consumed.

The main treatment involves a strict, low-carbohydrate diet to remove the yeast's food source. This is often combined with antifungal medications, such as fluconazole, and later, probiotics to restore a healthy gut flora.

In many cases, ABS can be successfully managed and put into remission with a combination of dietary changes, antifungal treatment, and probiotics. However, some individuals may experience relapses, and ongoing management and careful monitoring of the diet are often required to prevent recurrence.