Because both whey and casein proteins are derived from milk, the milk must undergo filtration processes to separate the two proteins. Although whey protein is highly refined and filtrated, there can still be trace amounts of casein protein present in all types of whey protein.
Whey also has higher levels of leucine, a potent amino acid that stimulates protein synthesis. Whey protein is superior at augmenting protein synthesis rapidly, .
While casein protein has been implicated in more cases of milk protein problems than whey, both milk proteins can cause similar issues. This is due to the fact .