But while some nutritionists have encouraged the protein craze, a number of experts are urging caution. They point out that protein powders and supplements, which come from animal products like whey and casein (byproducts of cheese manufacturing) or from plants like soy, rice, pea or hemp, are a relatively new invention. The vast majority of Americans already get more than the recommended daily amounts of protein from food, they say, and there are no rigorous long-term studies to tell us how much protein is too much.

https://www.nytimes.com/2016/12/06/well/eat/can-you-get-too-much-protein.html