Casein protein plays a critical role in healthy muscle development and growth. Several different types of casein proteins exist in milk, and these account for 70 to 80 percent of the substance. The protein structure of casein allows it to clot together, thus enabling cheese making. It is possible to obtain the amino acids found in casein protein from other sources, but casein remains an important protein source in many diets.
Nutritional Value
Along with whey, the other main protein found in dairy products, casein holds a high nutritional value. There are 20 amino acids that your body needs for growth and metabolism. Nine of these amino acids are termed "essential" because your body cannot synthesize them. Casein protein contains all of these essential amino acids. The World Health Organization assesses casein protein as being better quality protein than many other common sources, such as beef, black beans and peanuts.
Slow Digestion Rate
In his 2007 review of protein consumption, researcher Jay Hoffman notes that humans digest casein slowly over the course of several hours rather than in a couple hours like whey protein. This is due to casein's ability to clot in your stomach after you drink milk. Consuming protein with a slow digestion rate ensures that you maintain elevated amino acid levels in your blood, even when you must go long periods without food, such as when you are sleeping.
Muscle Growth
Casein can be a very important protein for a muscle-building program because of its slow and steady delivery of amino acid. A 2000 study published in the "Annals of Nutrition & Metabolism" examined the effect of casein protein supplementation and resistance training in overweight police officers. Subjects who consumed casein protein as a part of a calorie-restricted diet not only experienced weight loss, but they also had an average lean muscle mass gain of 4 kg after 12 weeks of training. These gains exceeded those made by subjects consuming a whey protein supplement.
Milk Allergy
Though casein protein can be a critical component of your diet, it is replaceable. Many people, especially children, are allergic to the casein and whey protein present in milk. If you have a milk allergy, the Children's Hospital of Pittsburgh recommends that you replace the casein in your diet with soy milk. Speak to a registered dietitian about your protein needs and what other foods you can consume to obtain all of your essential amino acids.
References
- University of Illinois: Milk Composition - Proteins
- "Journal of Sports Science and Medicine"; Protein - Which Is Best?; Jay Hoffman and Michael J. Falvo; September 2004
- Children's Hospital of Pittsburgh: Milk Allergy Diet
- "Annals of Nutrition & Metabolism"; Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers; Robert H. Demling and Leslie DeSanti; 2000
- "Strength and Conditioning Journal"; Protein Intake: Effect of Timing; Jay Hoffman, Ph.D.; 2007
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