What is Whey Protein?

• Whey protein is a mixture of globular proteins isolated from whey, the liquid material created as a co-product of the cheese making process. Whey protein is found naturally in cow's milk, which is made up of two proteins, casein and whey. However, whey is more soluble and easier to digest, and because of these factors it is often referred to as the "Gold Standard" of protein.
  
  

Proteins Found in Whey

• Whey protein is a complete protein that contains all 20 amino acids and all nine essential amino acids. As much as 30 percent of the amino acids in whey protein are branched-chain amino acids, including leucine, isoleucine and valine. Muscle cells can directly oxidize branched-chain amino acids, so they are used at a high rate during exercise. In addition, they have been shown to have the greatest positive effect on muscle protein synthesis among all of the amino acids.
  
  

Essential & Non-essential Amino Acids

• The nine essential amino acids that are found in whey include isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine and histidine. These are essential because the body does not synthesize them, therefore they must be supplied by dietary sources. Non-essential proteins found in whey are alanine, arginine, aspartate, cysteine, glutamate, gluatmine, glycine, proline, serine, asparagine and tyrosine. They are still very essential, but your body can naturally make them.
  
  

High-quality Protein Sources

• High-quality protein sources include meat, fish, poultry, eggs, milk, cheese and yogurt. Other food products that contain high amounts of whey protein include protein powders, drink mixes and energy bars. To find out if a product contains whey as a primary source of protein, check the ingredient list for "whey protein isolate," "whey protein concentrate" or "hydrolyzed whey protein" near the beginning of the ingredient list. However, whey protein isolate is the most pure and concentrated form of whey protein available, as it contains 90 percent or more of protein and very little fat and lactose.