Is protein powder safe? Here's the scoop I was an idiot and did fasting and worked out and lost a lot of muscle. I'm very upset. I just don't want to have any negative health consequences as a result of taking them. Other than protein powders, I eat extremely healthy. No oils, and 80/10/10. Any studies on the safety of protein powders? Also, what is the best vegan sources of protein powder? Would about soy, pea, and brown rice I was I was looking at. Any advice on what is best? What have you found to be most helpful to gaining muscle?