I tried several protein suppliments from GNC and none of them really did anything before I picked up the Nitro-Tech. Another problem is that I am lactose intolerant so I cannot have any product that requires me to mix with milk, or is composed entirely of whey, since whey is a deriviative of milk. For some reason when I take the Nitro though, I am fine. I have only tried the cell-tech for creatine, and yes it has worked for me, however, I am clueless as to what else to consider trying. Every time I go into GNC to buy something they try and talk me into buying their "GNC brand name" stuff. I always get the feeling that they are making money off of me or something if I do that, and thus, dont have my best interests in mind.