Auto-Brewery Syndrome: Fail a Breathalyzer without Drinking!

Endogenous alcohol is ethanol that is produced naturally in all living humans. The resulting blood alcohol concentration (BAC) is generally  low. However, auto-brewery syndrome is associated with very high BACs. It occurs after eating meals rich in carbohydrates.

Although everyone has endogenous alcohol in their bloodstream, auto-brewery syndrome is rare. Its origin is in the small bowel. There, very high levels of gastrointestinal yeast convert carbohydrates into ethanol. A  type of yeast, Saccharomyces cerevisiae is  the major cause of this condition.

Auto-brewery syndrome is different from the usual fermentation in the large bowel. Normal yeast levels in the large bowel produce ordinary endogenous alcohol.

The Study

This study investigated the effect of diabetes mellitus, liver cirrhosis, and presence of both on BAC after consuming a carbohydrate-rich meal.

Studied were controls, those with diabetes, those with liver cirrhosis, and those with both diseases. After they consumed large quantities of carbs, their BAC was measured. The BAC of the controls was the lowest. The BAC of those with either diabetes or liver cirrhosis was significantly higher. The highest BAC was among those with both diseases.

auto-brewery syndromeDrivers with diabetes or liver cirrhosis should be aware that eating eating meals rich in carbohydrates can increase their BAC. This is especially the case if they suffer from both diseases.

auto-brewery syndrome

Saccharomyces cerevisiae

Source: Hafez, E., et al. Auto-brewery syndrome: ethanol pseudo-toxicity in diabetic and hepatic patients. Hum. Exp. Toxicol. 2016. DOI
10.1177/0960327116661400. PMID 27492480.

Note: Liver abnormalities that prevent the body from breaking down alcohol normally can also cause high BAC without drinking.


Adams, C. Designated drunk: Can you get intoxicated without actually drinking alcohol? The Straight Dope, Oct 20, 2006.

Doucleff, M. Auto-Brewery Syndrome: Apparently, You Can Make Beer In Your Gut. NPR, Sept 17, 2013.

Geertinger, P., et al. Endogenous alcohol production by intestinal fermentation in sudden infant death. Zeitswchrift fur Rechtsmedizin, 1982, 89(3), 167-172.

Kaji, H., et al. Intragastrointestinal alcohol fermentation syndrome: Report of two cases and review of the literature. J Foren Sci Soc, 1984, 24(5), 461-471.

LaMotte, S. Woman claims her body brews alcohol, has DUI charge dismissed. CNN Health, Jan 1, 2016.

Logan, B. and Jones, A. Endogenous ethanol ‘auto-brewery syndrome’ as a drunk-driving defence challenge. Med Sci Law, 2000, 40(3), 206-215.

Thompson, H. The Man who gets drunk on chips. BBC, March 5, 2015.