Though near 240 amino acids have been discovered in nature but solely twenty of these are needed for human growth. These twenty amino acids are divided into 2 kinds: essential and nonessential.
Essential amino acids should be gotten from the diet. These contain threonine, leucine, lysine, methionine, valine, isoleucine, tryptophan, and phenylalanine.
There is also one element, histidine, that is called semi-essential, because it's important for development of kids.