Protein: More than just a juicy steak!

       Protein. What is it? Why do we need it? Do I have to eat steak all the time?!

       Like water, protein is a part of everything in our bodies. Everything from cells, tissues, organs and even hormones and DNA! Proteins are composed of chains of amino acids. There are 20 amino acids that combine to make a protein. Most proteins our bodies can manufacture; however, there are a few "essential" amino acids that our bodies cannot produce and must be provided through our diet. When considering dietary sources of protein, there are two types "compete" and "incomplete" proteins. Complete proteins contain all the essential amino acids our bodies require, whereas incomplete proteins are lacking one or more of the essential amino acids. (Centers for Disease Control and Prevention, 2011)

       Dietary sources of "complete proteins" include meat (beef, lamb, pork, game, etc), poultry, fish and other seafood, eggs, and dairy products. Incomplete sources of dietary protein include grains, legumes, some vegetables and fruits (although in very small amounts). Common combinations of incomplete proteins to make complete proteins include rice and beans or corn and beans (i.e. Spanish rice and refried beans or chili and cornbread). Soy and quinoa are the only plant-based proteins that are considered a complete protein (Complete protein, n.d.). For this reason soy is a staple of many vegetarian and vegan diets.  

       Protein has many functions throughout the body. Our muscles and organs are protein, the collagen in our skin and bones is a type of protein, even our DNA is a protein. Proteins can even be bad, like prions and the proteins of cancer cells. In the context of bone and muscle development, protein is an important nutrient for the maintenance and repair of muscle and bone. Without adequate protein in the diet lean muscle mass is sacrificed to maintain more vital functions within the body and can contribute to weakened bones (Bonjour, 2005; Houston, et al., 2008).

References

Bonjour, J.-P. (2005). Dietary Protein: An Essential Nutrient For Bone Health. Journal of the American College of Nutrition, 24(6), 526S-536S.

Centers for Disease Control and Prevention. (2011, October 31). Nutrition for Everyone: Basics: Protein. Retrieved from http://www.cdc.gov/nutrition/everyone/basics/protein.html

Complete protein. (n.d.). Retrieved 9 12, 2012, from Wikipedia: http://en.wikipedia.org/wiki/Complete_protein

Houston, D. K., Nicklas, B. J., Ding, J., Harris, T. B., Tylavsky, F. A., Newman, A. B., . . . Kritchevsky, S. B. (2008). Dietary protein intake is associated with lean mass change in older, community-dwelling adults: the Health, Aging, and Body Composition (Health ABC) Study. American Journal of Clinical Nutrition, 87, 150-155.