Moderate alcohol consumption actually increases longevity: http://en.wikipedia.org/wiki/Long-term_effects_of_alcohol. So regular periodic consumption of a reasonable amount of alcohol is actually helping you.
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.