I guess it depends on what you mean by "helped". I've seen a few figures, none of which indicated that it had no effect on alcohol consumption in the US, and none of which indicated that it came anywhere close to eradicating alcohol consumption, either. It's naturally hard to estimate, given that it was all done clandestinely so there aren't really any official figures to use, but I got the impression that you could say with some measure of confidence that it reduced consumption by somewhere between 30% and 70%.