Who can benefit from L-Lysine supplements? People with metabolic disorders, cases of lysine deficiency, those who want to increase the calcium levels in the body, athletes and active people who want to improve their physical performance, and people who want to reduce their anxiety and stress. Dietary inadequacy of essential amino acids, such as L-lysine, leads to nonspecific signs of protein deficiency, such as lowered resistance to disease, decreased blood proteins, and stunting in children. Other symptoms could include: fatigue, poor concentration, irritability, nausea, red eyes, hair loss, anorexia, anaemia, and problems with the reproductive system. Did you...