This Gut Pathogen Brew Alcohol From Carbs and Makes A Person Drunk


“But I didn’t drink!"
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A 2019 Case Report

One morning in 2014, a 46-year-old man got arrested for drunk driving. His blood-alcohol level was very high, at 200 mg/dL. Yet he told the hospital staff and police that he didn’t drink any alcohol. Of course, everyone thought he was drunk.

The man was soon referred to an Ohioan physician who had previously seen such a bewildering case. Every medical test appears normal except that Saccharomyces cerevisiae (brewer’s yeast) and Saccharomyces boulardii were detected in his stool samples. Give him a carbohydrate-rich meal and he became drunk. He was diagnosed with an auto-brewery syndrome (ABS), also known as gut fermentation syndrome.

Healing him was not easy. It required careful timing and dosage of antifungals targetting the nasty yeasts, probiotic Lactobacillus acidophilus to compete with the yeasts, and carbohydrate exclusion, and then gradual introduction over time. The entire process took 4 years.

“For years, no one believed him,” says the lead case study author, Fahad Malik, a chief medical resident at the University of Alabama, Birmingham. “The police, doctors, nurses, and even his family told him he wasn’t telling the truth, that he must be a closet-drinker.”

How did he get ABS? “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,” the authors of the case report explained.

Indeed, the man took cephalexin for 3 weeks for a thumb injury back in 2011. Ever since he experienced side effects of brain fog and depression usually after meals. And in 2014 he was arrested for presumed drunk driving.
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ABS Explained

It’s a rare medical condition that is underdiagnosed. Causes of ABS are yeasts — S. cerevisiae, S. boulardii, and Candida species — capable of fermenting carbohydrate to make ethanol. Other contributors include bacteria such as Klebsiella pneumonia and Enterococcus faecium.

Studying the lifestyle of people with ABS, researchers noted several things in common: poorer general health, more food sensitivities especially starch, bad breath, frequent diarrhoea, comorbidities of diabetes, obesity, and Crohn disease, and long-term usage of antibiotics.

Most antibiotics don’t discriminate between pathogens and friendly gut microbes — leading to depletion of major keystone species that normally outgrow and suppress pathogens. Antibiotics, therefore, provides the gut pathogens with a chance to dominate the gut microbiome.

Despite curing ABS with proper diet, antifungals/antibiotics, and probiotics, relapse can still happen. Refraining from carbohydrates as much as possible for a few months after ABS dissipates is recommended.

ABS and Fatty Liver

These gut pathogens brew alcohol which increases alcohol levels in the blood. ABS, therefore, mimics the harmful consequences of alcohol, but with carbohydrates instead.

Published in the prestigious Cell Metabolism in October 2019, a team of Chinese researchers found that people with fatty liver disease (FLD) were 10-times more likely to harbour the high-alcohol-producing strain of Klebsiella pneumoniae than healthy controls. Those with FLD also had 3.5-fold higher blood alcohol levels than controls upon consuming a sugary beverage.

To get a hint at causality, the researchers transferred Klebsiella pneumoniae — isolated from one participant with FLD and ABS— into the mice gut. All the mice developed a fatty liver. The extent of liver damage depended on how much carbs were consumed. These mice had FLD and ABS.

“These results suggest that at least in some cases of non-alcoholic FLD, an alteration in the gut microbiome drives the condition due to excess endogenous alcohol production,” the authors explained.
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The Spectrum

Some gut pathogens brew alcohol from carbohydrates. While this is true, the concern lies in their prevalence or relative abundance. On the drastic end, too much of such alcohol-brewing pathogens lead to full-blown FLD and ABS. On the lenient end, decent quantities of these pathogens may make one uncomfortable after a carbohydrate-loaded meal. This subclinical ABS may be one reason why it’s an underdiagnosed condition.

This article was previously published in Microbial Instincts with minor modifications.

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