you really cant mix it into most protein shakes as they typically contain glutamine (whey protein supplements) and L-Citrulline should not be taken at the same time as those, but i found that if you mix it into something with flavor (juice, ice tea, etc.) it goes down a lot easier, lol. The powder doesn't really mix well, or at least it doesnt dissolve easily so you almost need to mix it once, drink it, and then mix it again to get the left over powder.