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NOW L-Tryptophan 

Source of an essential amino acid for the maintenance of good health. Prior to 2012, the sale of L-Tryptophan was by prescription only, so consumers had limited access to this essential amino acid. Now that it is classified as a Natural Health Product, numerous consumers are expected to capitalize on the potential health benefits of oral tryptophan supplementation.

L-Tryptophan is a large neutral amino acid essential to human metabolism because it is the metabolic precursor of serotonin (a neurotransmitter), melatonin (a neurohormone), and niacin (vitamin B3) which assist in the regulation of sleep, positive mood and immune function. L-Tryptophan is not synthesized by the body and must be obtained from the diet. As a component of dietary protein, tryptophan is particularly plentiful in chocolate, oats, bananas, dried dates, milk, cottage cheese, meat, fish, turkey, and peanuts. It requires active transport and  competes for the same receptors with other neutral amino acids – tyrosine, phenylalanine, valine, leucine, and isoleucine, so a food that is high in tryptophan may not necessarily increase brain tryptophan and serotonin levels if it also contains a large quantity of these other amino acids. Tryptophan hydroxylase is the rate-limiting enzyme for serotonin production and involves the conversion of tryptophan to 5-hydroxytryptophan (5-HTP), which is then converted to serotonin. This enzyme can be inhibited by stress, insulin resistance, magnesium or vitamin B6 deficiency, or increasing age, so additional supplies of tryptophan may be required in certain circumstances. NOW L-Tryptophan is pharmaceutically pure and every lot is tested to be free of contamination from potentially harmful Peak E and microorganisms. This product contains the maximum daily dosage allowed by Health Canada for OTC sale.


Adult Dosage: Take 1 capsule daily with meals.

Ingredients (each capsule contains):

L-Tryptophan……………………………………………………..220 mg

Non-Medicinal Ingredients:

Veg Capsule (hypromellose, water), Cellulose, Stearic Acid, Hydroxypropyl Methylcellulose.