It has two main functions in the body, it is used as a building and repair material for tissues and organs, eg. There are many types of protein including, animal protein, plant protein, human protein amongst a few. They can all be made from the same 20 amino acids in long multiple chains. These can be arranged in any order and there maybe several hundred amino acids in a single protein molecule. The body can produce many of the 20 amino acids but there are eight essential amino acids that the body relies on from foods for its source, namely, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Children also require two further amino acids, histidine and arginine.
Each of these amino acids have their own specific function, as do the other less essential amino acids for example GABA and tyrosine, which are also essential to health. They have a good balance of the essential amino acids and are in similar proportions to those found in human tissues, muscles and organs. Eggs and human breast milk have the highest NPU ratings of all foods and are therefore classified as complete protein. Second Class protein or Incomplete protein are vegetable proteins, which are grains, nuts, pulses and seeds. They are classified as incomplete protein because these foods by themselves are low in one or more of the essential amino acids.