Protein is a structural component of the body from which formed its organs and tissues. Protein is required to replace or repair damages of cells and tissues. The main building material of protein is amino acids of more than twenty types. Plant and animal proteins differ from each other by the number of essential amino acids. Proteins of animal origin are found in dairy products, in all types of meat, poultry, fish, eggs and whey. The sources of plant proteins are beans, lentils, peas, soy beans, wheat, rice and nuts.