https://www.theregister.co.uk/2019/09/23/gut_microbe_alcohol_process/

Do you ever feel drunk, even though you swear you haven't touched a drop of alcohol at all? Well, your gut might be harbouring a type of bacteria that brews booze as a byproduct.

A team of Chinese scientists have written about the phenomenon after finding a patient with odd symptoms. Every time the individual consumed high levels of carbohydrates, their blood alcohol concentration levels shot up to a 400mg/100ml (aka a BAC of 0.04) – considered a high blood alcohol concentration - despite keeping an alcohol-free diet. They also found excess amounts of Klebsiella pneumoniae in their gut, a type of bacteria that produces alcohol from sugar and is normally kept in balance by the microbiome in the gut.