Metabolic Maintenance L-Phenylalanine 500mg supports balanced mood, mental clarity and focus. It helps support the normal production of mood-elevating chemicals in the brain such as dopamine and norepinephrine. L-Phenylalanine is an essential amino aicid that converts to tyrosine. The L form helps support normal mood and attention. It should not be used with MAO inhibitors or tricyclic antidepressants, or by patients who have PKU, or hypertension. Recommended Use: Take 1 to 2 capsules daily, or as directed by a healthcare professional. Best taken between meals.