Do vitamins work to improve mental focus? B-12, Ginseng, or whatever? / Are top rated players taking vitamins to improve their performance? If anyone has any info on this subject please share. Much appreciated.
Of all legal and easily available "supplements", one that can plausibly improve chess performance is caffeine. I have no hard data on this, but an excess might increase blunder rate, and is not very healthy in general.
I was referring to, maybe slightly racily, the fact that Germans, in my experience, tend to start alternations (Be in world wars, fisticuffs, tomfoolery, etc.) and then don't realize or accept when its time to call it quits.