Protein is an essential nutrient found in every cell in the body and is a major component of skin, muscles, glands and organs. It supplies your body with amino acids, which are the building blocks necessary to form new muscle. Milk contains two major proteins, casein and whey. Both supply all of the essential amino acids, but they are two very different proteins. In general, your diet will supply adequate protein, although more protein may be necessary for bodybuilders or those trying to gain weight and improve muscle mass. Understanding the unique characteristics of casein and whey can help you decide which protein is right for you.
Casein
Casein is a high-quality protein with a complete amino acid profile, meaning it contains all the essential amino acids. Essential amino acids can't be produced by the body and must be obtained from food. Caseins are the predominant proteins found in milk, making up about 80 percent of the protein content. Most kinds of milk contain three to four different caseins. Calcium, phosphorus and some enzymes combine to form a casein micelle -- a structure that allows the casein molecules to remain suspended in water. These micelle clusters are responsible for milk's whitish color. Caseins coagulate in the stomach and as a result reduce protein breakdown. In other words, it is a muscle sparing protein.
Whey
Whey is a fast-digesting protein that makes up the other 20 percent of proteins found in milk. When dairy products like cheese are manufactured, the whey is separated from the caseins. This byproduct was once thrown away as a waste product, but now is vastly utilized in a variety of protein products, including body building supplements and meal replacement products. Whey is a high-quality, complete protein that digests rapidly once consumed. The rapid digestion and absorption of whey results in a prompt and significant increase in plasma amino acids.
Comparison
Although both casein and whey are excellent protein sources, the similarities end there. Casein provides a sustained release of amino acids, while whey supplies a quick and short-lived release. Because casein digests more slowly, it feeds your muscles for a longer period of time. This can also slow the digestion of other proteins taken with casein. Whey has a higher concentration of branched chain amino acids, which helps maintain muscle tissue and may delay fatigue after intense exercise. Whey contains greater levels of the amino acid leucine, which increases protein synthesis.
Considerations
If you are lactose-intolerant or hypersensitive to milk, you may experience symptoms associated with milk hypersensitivity after consuming whey or casein. Casein can aggravate allergy symptoms because it is an immune system irritant and stimulates the production of mucous, according to Dr. Andrew Weil, founder of Weil Lifestyle. While casein appears to be immune suppressive, Drs. Elson Haws and Buck Levin, authors of "Staying Healthy with Nutrition", maintain that whey supports the function of the immune system. Dr. T Colin Campbell, author of "The China Study", concluded that casein increases risk of certain cancers and promotes all stages of the cancer process.
References
- MedlinePlus: "Protein in the Diet"
- "The Health Professionals Guide to Dietary Supplements"; Shawn M. Talbott & Kerry Hughes; 2006
- DrWeil.com: "Whey Better Protein?"
- Natural Standard: "Whey Protein Monograph"
- "Staying Healthy With Nutrition"; Elson Haws & Buck Levin; 2006
- "The China Study"; T. Colin Campbell & Thomas M. Cambell II; 2006
Member Comments