Why do you have to blind it?
To make it most realistic, you would not only give the treatment group alcohol, you would tell them that controlled trials suggest that this treatment (self-referentially) will reduce all-cause mortality.
An unblinded study would not be able to account for placebo effects.
My roommate recently sent me a review article that LW might find interesting:
Personal observation says that LWers tend not to drink very much or often. Perhaps that should change, to the degree suggested by the article?
Full article here.