Did you know that 9 out of 10 people lack the proper amount of protein in their systems in order for their bodies to function properly? Amino acids are concentrated in protein-rich foods such as meat, fish, and soybeans. Some people also take certain amino acids in supplement form as a natural way to boost athletic performance or improve mood. Amino acids are organic compounds that contain amino and carboxylate functional groups, along with a side chain (R group) specific to each amino acid.