Protein are the major structural and functional bio-molecules in the cell. They form cytoskeleton that maintains cellular shape and physical integrity of the cell and are essential constituents of the connective tissue. They function as an enzymes, hormones and immunoglobulins. They are responsible for muscle contraction and transport of oxygen (hemoglobin). Proteins are made up of chains of nitrogen-containing amino acids, which are divided into two categories—essential and non-essential amino acids. Of the 20 amino acids found in proteins, nine of them are essential (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) as cannot be produced by the body and they must be consumed in the diet. Proteins are required for normal growth, development and recovery from illness.