D,L-Phenylalanine (500 mg 100 capsules) - LifeExtension -

L-phenylalanine is an essential amino acid that can be converted to L-tyrosine by a complex biochemical process which takes place in the liver.

L-tyrosine can be converted by neurons in the brain and in the adrenal medulla of the adrenal glands to dopamine, norepinephrine (noradrenaline), and epinephrine hormones that are depleted by stress, overwork and certain drugs. By replenishing norepinephrine in the brain, mental energy levels are enhanced and a feeling of contentment often occurs. Because of the liver conversion necessary for L-phenylalanine to have these effects, L-tyrosine is often faster acting. In addition, the conversion step from L-tyrosine to norepinephrine may be enhanced if the co-factors (vitamins B6 and C) are included.

Cells in the adrenal medulla synthesize and secrete norepinephrine and epinephrine. Since both norepinephrine and epinephrine can cause smooth muscle (arterial) contraction, care with blood pressure should be taken when supplementing with L-phenylalanine or L-tyrosine.

L-tyrosine is also a precursor of two thyroid hormones.

Those who supplement with NAC should drink six to eight glasses of water daily to prevent cysteine renal stones. Cysteine renal stones are rare but do occur.