L-Tryptophan: benefits, dosage, contraindications
Other name(s)
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Scientific name(s)
L-2-amino-3- (indole-3-yl) propionic acid
Family or group:
Amino acids
Indications
Rating methodology
EFSA approval.
Smoking cessation ✪✪✪✪✪
Daily supplementation with tryptophan (50 mg/kg) for 2 weeks helps facilitate smoking cessation.
Posologie
Orally
50 mg/kg
2 - weeks
Premenstrual syndrome ✪✪✪✪✪
According to a study, taking L-tryptophan reduces mood swings, irritability, and tension in severe cases of premenstrual syndrome. A study showed that taking L-tryptophan in premenstrual dysphoric disorder (a severe form of premenstrual syndrome with primarily psychiatric symptoms) improves irritability, tension, and mood lability. A dose of 6 grams per day was used during 17 days of the cycle, from ovulation until the third day of menstruation, for three consecutive cycles.
Posologie
Orally
6 g
Depression ✪✪✪✪✪
Studies suggest that L-tryptophan may enhance the efficacy of conventional antidepressants.
Posologie
Orally
300 mg
28 - days
Gastric ulcer ✪✪✪✪✪
Clinical research shows that taking 250 mg of L-tryptophan twice a day along with 20 mg of omeprazole twice a day for 21 days improves healing rates of ulcers compared to omeprazole alone in individuals with Helicobacter pylori-associated gastroduodenal ulcers.
Posologie
Orally
500 mg
21 - days
Sleep disorders ✪✪✪✪✪
Clinical research shows that taking 1 g of L-tryptophan orally 20 minutes before bedtime may improve insomnia, compared to placebo, in healthy individuals suffering from insomnia. Other clinical research indicates that taking 500 mg of L-tryptophan twice a day for 2 weeks may also improve drug withdrawal-related insomnia such as with ketamine.
Posologie
Orally
1 g
2 - weeks
Tryptophan intake in the US adult population is not related to liver or kidney function but is associated with depression and sleep outcomes
Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake
Tryptophan for the sleeping disorder and mental symptom of new-type drug dependence: A randomized, double-blind, placebo-controlled trial
Tryptophan-enriched cereal intake improves nocturnal sleep, melatonin, serotonin, and total antioxidant capacity levels and mood in elderly humans
Tryptophan for the sleeping disorder and mental symptom of new-type drug dependence: A randomized, double-blind, placebo-controlled trial.
Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake.
Sleep-inducing effect of L-tryptophane
Sleep-inducing effect of L-tryptophane
Sports performance ✪✪✪✪✪
Some clinical research suggests that taking 300 mg of L-tryptophan orally with a sweet and electrolyte-rich drink twice a day for 3 days before exercise and on the day of exercise improves power output during the last 20 minutes of exercise, compared to taking the drink alone.
Posologie
Orally
300 mg
4 - days
Properties
Essential
L-Tryptophan is an essential proteinogenic amino acid. Apart from its proteinogenic role, tryptophan is involved in two important metabolic pathways: • The tryptophan pyrrolase pathway leads to the synthesis of niacin (vitamin B3). Practically, it is estimated that 2/3 of the net niacin requirement is covered by tryptophan metabolism in this pathway, with the remaining 1/3 needing to be supplied as dietary nicotinamide or nicotinate. • The other major pathway involves an initial hydroxylation reaction catalyzed by tryptophan hydroxylase, leading to the formation of 5-hydroxytryptophan (5-HTP). 5-HTP is then decarboxylated to form 5 hydroxytryptamine or serotonin, which is a neurotransmitter and a compound inducing smooth muscle contraction. Serotonin can be catabolized by monoamine oxidase or converted to melatonin via acetylation then methylation. Melatonin is a neurohormone involved particularly in the regulation of biological rhythms. Tryptophan is therefore the indispensable precursor of several particularly important compounds in the body. The Committee on Toxicity (COT) affiliated with the Food Standards Agency has set the consumption limit at 220 mg.day-1 for dietary supplements. However, the Afssa estimates the needs for this amino acid at 4 mg/kg/day.
Sedative
L-Tryptophan can cross the blood-brain barrier and convert to serotonin in the brain, which may explain its sedative effect.
Usages associés
Neurological
Reduction in endogenous tryptophan may provoke the relapse of treated depression or precipitate depressive symptoms in patients with personal or familial history of depression, as well as in healthy individuals. Moreover, dietary depletion of L-tryptophan has been associated with a relapse of bulimia and worsening of schizophrenia symptoms.
Safety dosage
Adult from 18 years: 220 mg
The Committee on Toxicity (COT) affiliated with the Food Standards Agency has set the dose of 220 mg/day as the consumption limit of L-tryptophan in dietary supplements. However, the Afssa estimates the needs for this amino acid at 4 mg/kg/day, approximately 200 mg/day.
Interactions
Médicaments
Antidepressant: moderate interaction
Combining a serotonergic antidepressant with L-tryptophan may increase the risk of serotonergic side effects, particularly cerebrovascular vasoconstrictor disorders.
Benzodiazepines: moderate interaction
The combination of L-tryptophan and benzodiazepines can cause reversible dyskinesias and reversible Parkinson-like rigidity.
Central Nervous System depressants: strong interaction
Theoretically, the concomitant use of sedative-producing medicines can have additive effects when taken with sedative-producing drugs. L-tryptophan can cause fatigue and drowsiness. Theoretically, the combination of L-tryptophan and a sedative-effect drug such as clonazepam, lorazepam, phenobarbital, zolpidem, and others, can increase sedation leading to fatigue and drowsiness.
Contraindications
Pregnant woman: prohibited
Taking L-tryptophan orally during pregnancy can cause in utero respiratory depression.
Breastfeeding woman: prohibited
It is advisable to avoid L-tryptophan intake in breastfeeding women due to lack of reliable information.
