Protein is a critical ingredient for sports enthusiasts looking to stimulate muscle growth and recovery; however, selecting the right protein source can be a challenge. Phil Wagner, M.D., director of SPARTA Performance Science, examined the category for the Mercury News, focusing on the most common options—whey, casein and soy.
Both casein and whey are dairy derived; casein is the major protein in milk and is released slowly into the bloodstream after ingestion, while whey protein has a high biological value and excellent bioavailability, making it a “fast” protein. Soy protein, extracted from the soy bean, is the third major protein seen in sports products, and is also taken up into the system quickly.
When selecting a protein source, Wagner advised consumers to look at several considerations. One is the rate of uptake, which is related to muscle protein synthesis; a 2009 study indicated subjects using whey had significantly greater muscle growth/repair at rest and after exercise compared to soy and casein. Whey also contains a host of factors that bolster immune function. However, Wagner also noted soy tends to have lower fat and cholesterol content, and is plant-derived, an issue for some athletes; it can be highly allergenic, as well.