Originally Posted by yauncin
Protein powder is a great source of protein but too much can put a strain on your liver and kidneys.
It's really hard to eat enough protein to do this. As it is, the body has very tight control over protein intake (try to eat more than one plain, dry chicken breast). Only people that have pre-existing kidney conditions need to be concerned about protein intake even at low levels. Ordinary folk increase their filtration rates with increased protein intake, but that doesn't necessarily translate into real kidney damage unless you're getting more than 2-3g of protein/lb bodyweight (something that is easily achieved on the SAD diet with a couple grease-tastic burgers a day, but I think we're all better than that). I shoot for a minimum .75g/lb but my goal is 1g/lb.
Also, protein isn't metabolized in the liver at all, so there's no risk there. If you want to protect the liver then watch out for excessive fructose consumption. It's about as bad for your liver as alcohol is. Check out this lecture
by Robert Lustig, an endocrinologist from UCSF about the dangers of fructose.