Hello, Whey protein is the protein contained in whey, the watery portion of milk that separates from the curds when making cheese. Whey protein is used for improving athletic performance, as a food supplement, as an alternative to milk for people with lactose intolerance, for replacing or supplementing milk-based infant formulas, and for reversing weight loss . Whey protein is likely safe for most children and adults when taken by mouth appropriately. High doses can cause some side effects such as increased bowel movements, nausea, thirst, bloating, cramps, reduced appetite, tiredness (fatigue), and headache. If you are allergic to cow's milk, avoid using whey protein. It will affect kidney too if you take concentrated mixture, drinking enough water will avoid that. For improving athletic performance: 1.2-1.5 grams/kg of whey protein in combination with strength training for 6-10 weeks is advisable dose for oral intake.