Not saying this to be a dick, but a kid I know is another health and fitness freak, and workouts 5 days a week eats clean, walks around with a gallon of water, he's all natural and about 6 months ago his kidneys started going out in him, his doc told him to stop drinking muscle milk in particular because of not the protein itself but there is another ingredient in muscle milk that is hard on the kidneys. Dude was pissing blood No joke he quit and switched to OPtimum nutrition and hasn't had a problem since.