Proteins are involved in virtually all biological processes, making amino acids fundamental to the structure and function of living organisms. There are amino acids that the human body cannot synthesize on its own and must be obtained from the diet or through dietary supplementation. There are amino acids that can be synthesized by the body, including amino acids like alanine, aspartic acid, and glutamic acid.  Amino acids play a variety of roles in the body, both as building blocks of proteins and as individual molecules. These roles include structural support, enzymatic functions, hormonal and neurotransmitter balance, metabolic regulation and many others. As individual molecules, amino acids can have unique mechanisms of action. For example: 5-HTP, a derivative of the amino acid tryptophan, is a precursor to serotonin and thus can affect mood, sleep, and other serotonin-related functions. L-tyrosine is a precursor for the neurotransmitters dopamine, norepinephrine, and epinephrine, thereby affecting mood and stress responses. Acetyl l-carnitine is involved in fatty acid metabolism, helping to transport fatty acids into the mitochondria for energy production.