Auto-brewery syndrome (ABS), also referred to as “gut fermentation syndrome,” is a rare, but likely underdiagnosed condition where an overgrowth of yeast and/or fungi residing in the gastrointestinal tract converts the intake of dietary carbohydrates into endogenous alcohol, without consuming any alcohol. The excessive production of ethanol (a type of alcohol) by yeasts in the gut eventually enters the bloodstream, causing the same physical and psychological manifestations as someone who has been drinking. The symptoms of this strange syndrome are very similar to those seen in Candida overgrowth. Although the diagnostic criteria of ABS involves an overgrowth of fungal species in the GI tract, not all cases of yeast overgrowth manifest in symptoms associated with excessive alcohol ingestion, such as slurred speech, delirium, mood changes, and dizziness; both conditions often do share symptoms (aside from GI problems) of cognitive disturbance including “brain fog,” chronic fatigue, difficulty concentrating, poor memory, and in many cases, depressed moods.

Potential contributing factors of ABS are frequent or long-term antibiotic use and excessive or regular consumption of foods high in sugars and simple carbohydrates. Research shows that those diagnosed with ABS often report consuming high sugar, high carbohydrate diets. If a patient appears to have signs and symptoms mentioned above (and reports consuming no alcohol), it is imperative that a functional stool test is performed to check for abnormal levels of bacteria, fungi, and other pathogens, in addition to the carbohydrate challenge test to check blood alcohol levels. Elevated levels after ingestion of carbohydrates and sugar may indicate ABS. It is important that health care practitioners run additional blood and urine tests to rule out underlying conditions that could explain symptoms.

The first line of action should be to test and treat any underlying medical conditions that may be the cause of ABS, including microbiome imbalance, weakened immunity, or inflammatory bowel diseases. In cases of patients who test positive (via stool analysis) for fungal overgrowth of Candida and/or Saccharomyces families, which are commensals that can become pathogenic as they can convert dietary carbohydrates to endogenous alcohol, a combination of pharmaceutical and herbal antifungals, in addition to dietary changes, may be necessary to restore balance in the intestines. Obviously every patient has biochemical individuality, thus treatment plans will be unique for each patient.

Similar to that of the anti-candida diet, patients need to avoid simple carbohydrates such as sugars and refined foods and follow a low-sugar diet avoiding sodas, juice, fruit, flour, pastries, bread, alcoholic beverages, and even certain “health” foods like fermented foods (e.g., kimchi, sauerkraut, kvass, yogurt, kefir, kombucha) that may exacerbate the condition since these fungi proliferate by feeding on these foods and drinks. It is recommended that a high fat, very low carb (e.g., ketogenic) diet be implemented for ABS until bacterial levels normalize and symptoms resolve. Utilizing natural sugar alternatives such as the herb stevia is a safe, good choice for those trying to reduce sugars due to yeast overgrowth. Herbal antifungals and antimicrobials, such as garlic, may accelerate the process without causing harm to the liver or intestines (a result of many prescribed drugs) by maintaining the integrity of the gut microbiome and not killing the commensal/beneficial bacteria species. The mono-ester, monolaurin, that can be found in coconut oil has been shown to possess impressive antimicrobial and antifungal properties and has much greater antiviral activity than isolated lauric acid alone, and poses no threat to the beneficial intestinal flora.

Several probiotic strains are shown to be effective for yeast overgrowth, including B. subtilis, a spore-based probiotic that is able to produce various antimicrobial and antifungal lipopeptides that help balance the internal bacterial flora within the host. In a case report of a 46-year-old male diagnosed with ABS, after taking rounds of antifungal drugs to competitively inhibit the fungi and help normalize the microbiome, he was given a 3 billion CFU single-strain Lactobacillus acidophilus, and after 6 weeks, it was changed to a multi-strain probiotic without fungi. He slowly reintroduced carbohydrates back in the diet, continues to take multi-strain probiotics and has remained asymptomatic since, according to the study. Because the health of the gut microbiome is a large determinant in the robustness and health of one’s immune system, it’s critical to focus on prevention through building a healthy immune system and avoiding the ideal conditions (mentioned above) for fungal overgrowth. 

By: Caitlin Higgins, MS, CNS, LDN