Protein is a key element in muscle repair and recovery. There are two main types of protein: whey and casein. Both whey and casein protein provide a complete amino-acid profile, the building blocks of muscle. There are, however, major differences between whey and casein protein, the most important being the absorption rate of each.
When discussing the different “types” of protein, it is important to consider that there is no such thing as just “protein.” Protein is a complex compound of amino acids and polypeptides that are unique to every source. Pork protein is different than beef protein, which is different than dairy protein. Whey and casein protein are only two examples out of the hundreds that exist.
Protein is important to muscle growth and function because it contains amino acids. There are 21 types of amino acids that the human body requires to function, nine of which are considered “essential.” Essential amino acids are acids that the body cannot create on its own, which then requires these acids to be consumed on a daily basis. Most quality whey and casein protein supplements contain an appropriate amount of all 21 amino acids.
Whey protein is the most common and generally useful form of protein. Whey protein is not common in natural foods. In fact, the only natural source of whey protein is milk, specifically from either a human or a cow.
By far, the most common form of whey protein is whey protein isolate. Whey protein isolate is a dry powder that is mixed with either water or milk and consumed as a nutrition supplement. Whey protein concentrate is much like protein isolate, except that it is a much purer form of protein and contains less lactose and other undesirable ingredients. Whey protein is far and away the most popular choice for protein supplementation due to its low cost and fast absorption rate of around one to two hours.
Casein protein is like whey protein in that it provides all of the necessary amino acids; however, casein protein takes a comparatively long time to be absorbed by the body. Casein protein is extracted from milk much the same way whey protein is, through the use of a screen that catches the large protein particles. After the protein has been separated from the milk, it is dried and sold as a powder to be mixed with water or milk. The main difference between whey and casein protein is that casein is absorbed by the body much more slowly, typically taking seven to eight hours.