Auto-brewery syndrome (ABS) is a medical condition that causes carbohydrates you consume to be fermented into alcohol in your gut. Also known as gut fermentation syndrome, this condition essentially makes you intoxicated, or drunk, without drinking any alcohol.
Your gut turns into a veritable brewery, creating many of the symptoms associated with heavy drinking or a hangover. Many of those affected have been arrested for driving while intoxicated and found to have alcohol blood levels far higher than the legal limit, although they had not had even one drink.
Such was the case of a 46-year-old man who is the subject of a case report in BMJ Open Gastroenterology, which suggests ABS may be more common than previously thought.1
ABS Is Difficult to Diagnose, Medical Staff Often Dismiss It
The man in the case study was previously healthy until he received antibiotic therapy for a traumatic thumb injury. One week later, he started experiencing personality changes, including episodes of depression, brain fog and aggressive behavior.2 His primary care physician evaluated this uncharacteristic behavior and sent him to a psychiatrist, who prescribed medications.
Eventually, he was arrested because police officers believed he was driving while intoxicated; his blood alcohol level was 200 mg/dL. At this level, a person will typically appear drunk and may be severely visually impaired. Vomiting, incontinence and symptoms of alcohol intoxication can also occur at a blood alcohol level starting at 200 mg/dL.3
Both the medical personnel and the police refused to believe that the man had not consumed alcohol, and this is a common theme in cases of ABS. After seeing multiple doctors, both brewer’s yeast (Saccharomyces cerevisiae) and another type of yeast (Saccharomyces boulardii) were detected in the man’s stool, and a diagnosis of ABS was made by monitoring his blood alcohol level following a meal of carbohydrates.
Treatment with antifungal drugs and a prescription for a carbohydrate-free diet were given, which worked to relieve the symptoms for a few weeks. Intermittent flare ups then began again, including one so severe it landed the man in the hospital due to a fall that caused intracranial bleeding. Even then, the case study noted, “the medical staff refused to believe that he did not drink alcohol despite his persistent denials.”4
It wasn’t until reading an online support group that the man contacted the researchers of the BMJ case study, who put him on a different antifungal therapy and, after its completion, started him on a probiotic that helped to restore his gut flora. According to the BMJ:5
“He was started on a probiotic (single-strain Lactobacillus acidophilus with 3 billion colony-forming units per capsule) to competitively inhibit fungi and help to normalise his gut flora. Carbohydrates were then gradually introduced in his diet, and a repeat carbohydrate challenge test was negative.
After 6 weeks, this probiotic was changed to a multi-strain probiotic, which contains 12 different bacterial organisms without any fungi. He has since continued this treatment. Approximately 1.5 years later, he remains asymptomatic and has resumed his previous lifestyle, including eating a normal diet while still checking his breath alcohol levels sporadically.”
Antibiotic Therapy May Have Triggered ABS
In this case study, the researchers believe the triggering event was the man’s antibiotic therapy, which altered his microbiome allowing for the fungus to thrive. Along with stating that ABS is likely an underdiagnosed condition, the researchers noted, “We believe that our patient’s symptoms were triggered by exposure to antibiotics, which resulted in a change in his gastrointestinal microbiome allowing fungal overgrowth.”6
This may be the first time antibiotics have been linked to the disease, although other research that compared patients with ABS to a group of healthy controls found that those with ABS reported using antibiotics for a longer time.7 According to one review, antibiotics use, along with a diet high in processed foods, could be to blame:8
“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.”
The use of probiotics to treat ABS is also an area that deserves further study, and it’s possible that fecal transplants could offer a successful treatment. In the featured study, the researchers started out with a single-strain probiotic supplement in order to competitively inhibit fungal growth, and then switched to a multistrain probiotic after six weeks, in order to support a diverse microbiome.
Because this condition may occur more often than realized, the researchers suggested that anyone who has elevated blood alcohol levels or a positive Breathalyzer but denies alcohol ingestion should be investigated for ABS. Further, they noted that symptoms such as changes in mood, delirium and brain fog may occur early on, even before symptoms of alcohol inebriation develop.9
In 2015, a New York woman who was charged with a DUI after a Breathalyzer showed she had a blood alcohol level more than four times higher than the legal limit had the case dismissed after a court heard evidence that she suffers from ABS.10
Is ABS Responsible for Rising Cases of NAFLD?
In another ABS case, a 27-year-old man in China with nonalcoholic fatty liver disease (NAFLD) was found to have extremely high blood alcohol levels of about 400mg/L after consuming a high-carbohydrate (but alcohol-free) diet.11 In this case, it wasn’t fungus that was driving the disease but bacteria known as Klebsiella pneumoniae.
The finding came after researchers compared samples of the man’s feces with that from people with NAFLD as well as a healthy control group. The man had higher levels of K. pneumoniae in his feces than the other groups; at the height of his ABS symptoms, nearly 19% of the bacteria in his feces was K. pneumoniae, which is 900 times higher than normal.12
Further, strains of K. pneumoniae that could generate high amounts of alcohol were isolated from the man and were found to be higher in those with NAFLD compared to the healthy controls. In patients with NAFLD, 60% had high-alcohol producing strains of K. pneumoniae, compared with just 6% of the control group. When mice were fed the high-alcohol producing bacteria, they also developed signs of liver damage.13
“These results suggest that at least in some cases of NAFLD an alteration in the gut microbiome drives the condition due to excess endogenous alcohol production,” the researchers concluded.14
ABS Is More Common in People With NAFLD
People with ABS are more likely to suffer from additional health conditions, including diabetes, chronic intestinal obstruction or liver dysfunction, such as NAFLD and nonalcoholic steatohepatitis (NASH).
NAFLD is the most common chronic liver disease in developed countries,15 characterized by a buildup of excess fat in your liver that is not related to heavy alcohol use. NAFLD can progress to NASH, a more severe form of the condition that involves inflammation of the liver and liver cell damage in addition to the buildup of fat.16
People with NASH may go on to develop fibrosis, or scarring, of the liver, as well as cirrhosis of the liver, which in turn is linked to an increased risk of liver cancer (rates of liver cancer have been increasing over the last two decades).17,18
NAFLD often has no symptoms, although it may cause fatigue, jaundice, swelling in the legs and abdomen, mental confusion and more. In the early stages, NAFLD may be reversed by careful attention to diet and exercise, and choline intake may also play a significant role.
Dietary Strategies Are Important
With NAFLD, the fatty liver occurs in the absence of significant alcohol consumption, and is driven instead by excess sugar. In cases of NAFLD, you need to eliminate processed fructose and other added sugars from your diet, which is also recommended for those with ABS.
Fructose affects your liver in ways that are very similar to alcohol. Unlike glucose, which can be used by virtually every cell in your body, fructose can only be metabolized by your liver, as your liver is the only organ that has the transporter for it.
Since all fructose gets shuttled to your liver, if you consume high amounts of it, fructose ends up taxing and damaging your liver in the same way alcohol and other toxins do. The way your liver metabolizes fructose is also very similar to that of alcohol,19 as both serve as substrates for converting carbohydrates into fat, which promotes insulin resistance, dyslipidemia (abnormal fat levels in the bloodstream) and fatty liver.
Fructose also undergoes the Maillard reaction with proteins, leading to the formation of superoxide free radicals that can result in liver inflammation similar to acetaldehyde, an intermediary metabolite of ethanol.
Reducing carbs to 50 grams for every 1,000 calories and increasing your intake of healthy fats is a powerful way to support your liver health and could likely benefit ABS as well, especially when combined with probiotics. As noted in one review:20
“An essential treatment of auto-brewery syndrome is diet modification requiring a high protein and low carbohydrates until symptoms subside. Sugar is fermented into alcohol, and a diet that eliminates simple and complex sugars will decrease the alcohol fermented from the gastrointestinal tract …
Multistrain probiotic supplements help balance bacteria in the gastrointestinal tract and have been used in the treatment of auto-brewery syndrome but have yet to be studied as a treatment … The risk of relapse of auto-brewery syndrome is lessened by avoiding carbohydrates.”
While it’s still unclear why some people develop ABS, it’s associated with metabolic disturbances such as diabetes and obesity, and those affected “often report a high-sugar, high-carbohydrate diet.”21 As mentioned, antibiotics use may also be a triggering factor, adding one more reason why their judicious use is important.
In another case study, a 45-year-old man with obesity and diabetes developed ABS symptoms, including vomiting, slurred speech, hallucinations and loss of consciousness after meals following treatment with two course of antibiotics for a deviated nasal septum and dental procedure. He was treated with an antifungal agent but also “responded dramatically” to a no-carbohydrate diet.22
If you or a loved one may be struggling with ABS, getting a correct diagnosis is crucial for recovery, as it’s often mistaken for alcohol consumption, leading to social and legal problems that can affect jobs, relationships and more. Further, even after ABS symptoms have resolved, the long-term exposure to ethanol can lead to addiction and alcohol cravings, leading to drinking,23 which is why getting holistic help is crucial.