Iodine with L-Tyrosine provides superior nutritional activity. Optimal levels of iodine benefit to enhance metabolism. L-Tyrosine is an important amino acid which is necessary for the body. Tyrosine is the precursor to the neurotransmitter, dopamine, which in turn is a precursor to the adrenal "fight or flight" hormones, epinephrine and norepinephrine. An increase in these adrenal hormones will suppress thyroid function. L-tyrosine is an amino acid necessary for the manufacture of thyroid hormones and can be taken alone or as a component of a nutritional supplement at a dosage of 500 mg per day to enhance thyroid function. The thyroid gland needs Iodine to make its hormones.