Amino acids are molecules that combine to form proteins and are also known as the basic building blocks of life. They have many different roles in the human body, each just as critical as the next. Our bodies use amino acids as neurotransmitters or to build proteins and hormones. They are essential for breaking down food and repairing body tissue. Amino acids are classified into three groups: Essential amino acids Nonessential amino acids Conditional amino acids Essential amino acids can't be produced naturally in the body and must be consumed through our diets.  Nonessential amino acids can be produced naturally in the body. Conditional amino acids are nonessential, except when the body is suffering from an illness and can't produce them naturally.