Where does whey protein comes from?

Answer 1

One view:

Whey protein is the name for a collection of globular proteins that can be isolated from whey, a by-product of cheese manufactured from cow's milk. It is typically a mixture of beta-lactoglobulin (~65%), alpha-lactalbumin (~25%), and serum albumin (~8%), which are soluble in their native forms, independent of pH. Whey has the highest Biological Value (BV) of any known protein.

Source: Answers.com

A complementary view:

All whey proteins are not the same. Denatured whey protein, that you buy in the health food store, will build muscle. Undenatured whey protein has a high amount of Branched Chain Amino Acids, (BCAA's)and a very high Biological Value (BV). In addition to building your muscle, it will also raise your glutathione levels.