If you are sweating a lot you will need to replace your potassium. As for other vitamins, if you eat well, clean, organic type foods and go easy on sugar, flour, etc. and you have no illness that you are dealing with, you may not need to supplement. I personally think the trend is to oversupplement, which makes the body weak and unable to meet those requirements itself. The idea is to tweak the body into doing the work itself rather than inundating it with a host of things that we may not need and could even unbalance our natural ecosystem.