Why Do We Need Amino Acids?

You might understand that there are approximately 250 amino acids in nature, but people use only 20 of them. People classify those amino acids into two kinds: essential and nonessential.

Essential amino acids are obtained from the diet. Threonine, leucine, lysine, methionine, valine, isoleucine, tryptophan, and phenylalanine are included into this type.

Histidine that's necessary for growth [...]