Protein
Proteins are complex organic compounds whose basic structure is a primary chain of amino acids folded into a certain shape. This tertiary fold dictates the function of the protein within the organism. They can take on many forms and perform distinct functions including (but certainly not limited to) structural, enzymatic and transportation roles. In terms of structure, proteins are important in the construction and integrity of different body tissues including connective and muscular, as well as endocrine/exocrine glands. [1]
Adult humans need a minimum of 1 gram of protein for every kilogram of body weight per day to keep from slowly breaking down their own tissues. Failure to receive enough protein can cause stunted growth, loss of muscle mass, decreased immunity, weakening of the heart and respiratory system, and eventually death. [2]
There are two types of amino acids: essential and non-essential.
There are 13 amino acids the body can manufacture on it's own. Essential amino acids are those which cannot be made by the body and can only be obtained from the diet. There are 9 amino acids the human body cannot produce on it's own. [3]
Protein is also classified as complete or incomplete.
Complete protein foods supply all of the essential amino acids the body needs to build new proteins. Incomplete protein foods do not supply all the essential amino acids.
Complete protein food sources tend to come from meat and other animal products, fish, eggs, and milk products. Incomplete proteins come from plant sources, fruits, vegetables, grains, and nuts. Plant proteins can be combined to include all of the essential amino acids and form a complete protein, such as eating rice and beans together. Protein is only one component of a healthy diet. [4]
