Phenylalanine (essential amino acid) is provided from the outside with food or synthetic products. Its source are the high-protein foods and supplements, concentrates: protein, amino acid and nutritional supplements for athletes. Precursor of tyrosine, thyroid hormones and neurotransmitters (adrenaline, noradrenaline, dopamine), phenylethylamines (neuromodulator) and melanin pigments of hair and skin. Essential for the proper functioning of the nervous system. It has analgesic, antidepressant, and is used as an additive to supplements with thermogenic and stimulating action. It is a component of aspartame.
Excess phenylalanine consumed by people with neurological problems, may reduce the availability of other essential amino acid tryptophan of nervous system and consequently lead to a reduction in serotonin and exacerbate the depression.