Amino acids are classified as either essential or non-essential. Essential amino acids cannot be synthesised in the body and must be obtained from the diet, whereas non-essential amino acids, whilst still essential for health, can be synthesised in the body and are therefore not classified as ´essential´. Tyrosine is considered a non-essential amino acid because the body can make it from phenylalanine. It is important to brain nutrition because it is a precursor of the neurotransmitters - dopamine, adrenaline and noradrenaline. It also acts as a precursor for certain hormones, including thyroxine and for the major human pigment melanin.As with all our amino acids, Lamberts L-Tyrosine is presented in its free-form for maximum absorption. IngredientsL-Tyrosine 500mg Other IngredientsEncapsulated with: Capsule Shell (Gelatin), Silicon Dioxide, Magnesium Stearate, Cellulose.Directions1 to 4 capsules daily with water or fruit juice. An amino acid is best taken half an hour before any meal or at bedtime.CAUTION: Not to be used with MAO inhibitors (a type of anti-depressant medicine). Do not take if pregnant or breast feeding.