personally i believe and know there are supplements that do help in different ways to produce,maintain and heal muscles.
think about this though. the "mental" part of lifting is one of the most important factors in lifting and putting on size,strength. when you buy a supplement you buy it with that mentality of "this is gonna make me grow". in affect raising your mental concentration and also raising your intensity. what am i saying?
if you could keep your mentality and intensity at say the same type of level,thought pattern as
taking supplements BUT not taking any at all how much of a difference would the supplements make? interesting thought i thought. would be interesting to see someone try this out.