Protein is present in all living organisms and is one of the three basic food groups along with carbohydrates and fat. Proteins are complex organic nitrogenous compounds that are the major source of building material for muscles, blood, skin, hair, nails and the internal organs.
Protein is made up of amino acids that have the elements carbon, hydrogen, nitrogen and oxygen.
Protein is essential for growth, the building of new tissue, and the repair of injured or broken-down tissue. Protein is made up of a combination of basic units called amino acids. There are 20 amino acids, of which nine are considered 'essential' and must be obtained from food because they cannot be synthesized in the body. The other 11 amino acids can be made in the body. Most food sources of protein contain nearly all of the 20 amino acids, although the ratio varies amongst sources.