I read an article just recently that argues that the reasonable amount may be much lower than many people think.

http://healthcorrelator.blogspot.com.au/2013/01/how-much-alc...

But there is little variation in one respect. The optimal amount of alcohol is somewhere around 5 and 7 g/d, which translates into about the following every day: half a can of beer, half a glass of wine, or half a “shot” of spirit.