Phenylalanine
PHENYLALANINE is an essential amino acid that is converted to tyrosine in the body. It is highly concentrated in the brain and plasma. Producing neurotransmitters, phenylalanine is used by the brain to manufacture norepinephrine, contributes to memory and learning, and controls obesity. It has been successfully used to treat mental problems, depression, and to depress the appetite. Free amino acids in the intestine, especially tryptophan and phenylalanine, trigger the release of cholycystokinin (CCK), which is thought to induce a "full" feeling. Normal metabolism requires biopterin, iron, niacin, Vitamin B6, copper, and especially Vitamin C.
The direct conversion of phenylalanine to tyrosine and then to dopamine and on to norepinephrine and epinephrine indicates its wide range of influence. The form of phenylalanine found in animal protein is left-handed, or L. That found in plants is right-handed, or dextro (DL), but can be converted in the body to the L form.
Because of its action in the central nervous system, this amino acid not only elevates moods enabling the individual to overcome depression, but also decreases pain associated with migraines, menstruation, and arthritis. It appears that the DL form has the pain-killing properties.
Deficiencies can occur if the enzyme that converts phenylalanine to tyrosine is absent. As stated, low phenylalanine levels are often found in depressed people. These levels are made even lower with the use of caffeine. On the other hand, if the overall protein diet is low and phenylalanine is taken in large doses, it not only causes an amino acid imbalance but will induce tyrosine toxicity.
Phenylalanine should not be used by pregnant women or those suffering from anxiety attacks, high blood pressure, pre-existing pigmented melanoma, or PKU (phenylketonuria). PKU (phenylketonuria) is an inborn error in phenylalanine metabolism and occurs in one out of every 20,000 to 40,000 live births in the United States. The result of this is severe mental retardation. When a phenylalanine-restricted diet is given from birth, mental development is normal. It is suggested that mild cases of PKU may be the underlying cause of hyperactivity, learning problems, and other developmental problems in children.
Other names for phenylalanine include: PHA, PHE, amino acid F, and 2-amino-3-phenyl propanoic acid.
Deficiency symptoms include: nervousness; clouded thought; emotional agitation; depression; behavioral changes; bloodshot eyes; cataracts; increased eating; and decreased alertness, memory, sexual interest, skin melanin, insulin production, and tyrosine formation.
Toxicity symptoms include: increased blood pressure and emotional agitation, insomnia, headaches, and tyrosine toxicity.
