Necessary for tissue and organ formation, cellular repair and hormone and enzyme production.  Provide energy, but not a primary function (4 kilocalories/gram)

Proteins are macromolecules composed of chains of basic subunits called amino acids.  Amino acids are composed of carbon, oxygen, hydrogen, and nitrogen.  Food sources of proteins include meats, dairy products, seafood, and a variety of different plant-based foods, most notably soy.  The word protein comes from a Greek word meaning “of primary importance,” which is an apt description of these macronutrients; they are also known colloquially as the “workhorses” of life.  Proteins provide the basic structure to bones, muscles and skin, enzymes and hormones and play a role in conducting most of the chemical reactions that take place in the body.  Scientists estimate that greater than one-hundred thousand different proteins exist within the human body.  The genetic codes in DNA are basically protein recipes that determine the order in which 20 different amino acids are bound together to make thousands of specific proteins.  Because amino acids contain carbon, they can be used by the body for energy and supply 4 kilocalories of energy per gram; however providing energy is not protein’s most important function.