Protein is a macronutrient that helps build muscle, control weight and keep your body healthy. Protein is mainly found in animal products such as meats and dairy products, but some plant sources provide protein as well. Milk contains two types of protein: whey and casein. Soy protein is a plant-based protein found in soybeans and soy products. These three types of proteins share similarities and have differences.
Whey is a protein found in milk and dairy products, along with casein. Whey protein makes up approximately 20 percent of the protein found in milk. Whey protein is considered a complete protein because it provides all of the essential amino acids required by the body. Whey protein is soluble, easy, and quick to digest, so it is commonly used in infant formulas and protein supplements.
Soy protein comes from soybeans. Soybeans are legumes that are low in fat and have zero cholesterol. Soy protein is often used as a replacement for animal proteins in vegetarians. Soy protein has been associated with a variety of benefits, including decreasing cancer risk, cardiovascular disease risk, obesity prevention and control, and improved health after menopause. Soybeans, soy milk and other soy products are sources of soy protein.
Casein is a protein found in cow's milk along with whey protein, but while whey is a fast digesting protein, casein is slow digesting which allows you to feel fuller, longer. Casein makes up approximately 80 percent of the protein found in milk. Casein is responsible for curd formation, which is the substrate that makes cheese. Casein plays a major role during growth and development due to its amino acid composition. There are generally three to four types of casein in milk.
Whey, soy and casein are all forms of protein. All are beneficial to the maintenance of muscle, health of the immune system and maintenance of blood sugar levels. All three forms of protein are available in natural forms and commercially produced supplements.
The major difference between the three types of protein are in the sources in which they are found. Both casein and whey are found in milk, and soy protein is found in soybeans. Casein and whey may be acceptable to vegetarians who consume milk and dairy products, but many vegetarians opt to use soy protein as their major dietary protein source.