Tryptophan is an essential Amino Acid. It is a precursor for serotonin (which aids sleep and anxiety), and helps in niacin (B vitamins) production. Foods that are considered sources of tryptophan are dairy products, beef, poultry, barley, brown rice, fish, soybeans, and peanuts. L-tryptophan is a natural sedative. It is normally found in turkey meat, and many people believe it to be the cause of a sleepiness common after a Thanksgiving feast.
Warnings: Pregnant or lactating women, diabetics, hypoglycemics, and people with known medical conditions and/or taking drugs should consult with a licensed physician and/or pharmacist prior to taking dietary supplements.
L-tryptophan - 500 mg, California Natural, 60 Capsule
For many organisms (including humans), tryptophan is an essential amino acid. Thismeans that it cannot be synthesized by the organism and therefore must be part of its diet. Amino acids, including tryptophan, act as building blocks in protein biosynthesis. In addition, tryptophan functions as a biochemical precursor for the following compounds (see also figure to the right):
Serotonin (a neurotransmitter), synthesized via tryptophan hydroxylase. Serotonin, in turn, can be converted to melatonin (a neurohormone), via N-acetyltransferase and 5-hydroxyindole-O-methyltransferase activities.
Niacin is synthesized from tryptophan via kynurenine and quinolinic acids as key biosynthetic intermediates.
Auxin (a phytohormone) when sieve tube elements undergo apoptosis tryptophan is converted to auxins.
The disorders fructose malabsorption and lactose intolerance causes improper absorption of tryptophan in the intestine, reduced levels of tryptophan in the blood and depression.
In bacteria that synthesize tryptophan, high cellular levels of this amino acid activate a repressor protein, which binds to the trp operon. Binding of this repressor to the tryptophan operon prevents transcription of downstream DNA that codes for the enzymes involved in the biosynthesis of tryptophan. So high levels of tryptophan prevent tryptophan synthesis through a negative feedback loop and, when the cell's tryptophan levels are reduced, transcription from the trp operon resumes. The genetic organisation of the trp operon thus permits tightly regulated and rapid responses to changes in the cell's internal and external tryptophan levels.