Origin and definition
L-tyrosine is an amino acid that occurs naturally in the body. It is considered semi-essential because the body can synthesize it from another amino acid, phenylalanine, but this production can become insufficient during periods of intense stress, prolonged fatigue, or high mental demand. L-tyrosine is now widely used in micronutrition to support concentration, alertness, andnervous system balance, particularly during periods of intellectual or emotional stress.