I'm pretty sure someone tried to use this as a defence in a drink drive case some years ago and it made the news. I can't remember what the outcome was though.
Logically if you are producing alcohol in the gut you'll be adsorbing some but still piss out a weak solution, maybe that's how they make Fosters :wha:
I know someone who "suffered" the same problem. He used to drink a fairly large amount of Abbot ale, cask conditioned, and after several months of hospital tests they clamed his stomach was not breaking down the yeast. He switched to keg beers, end of problem.