I'm no expert but I think it's perfectly ok/healthy even to incorporate protein powder into your diet. When I am working out/weight-lifting 2-3 times a week, I'll have several protein shakes (Whey Protein). However, I'm not sure if it's healthy to use Protein powder for ALL your protein needs, i.e. replace "natural" protein-rich foods with (just) powder. You often read on these things that the powder is not supposed to replace a well-balanced diet. You can probably find out more by checking out sites/stores like Holland and Barrett, who sell protein powder. They're mainstream enough (and sell enough protein powder) to suggest that protein powder is widely accepted as safe/healthy, but I think they'll also say that it's not supposed to completely replace natural protein sources. Anyway, best of luck in your research!