L-Tryptophan: benefits, dosage, contraindications
Scientific name(s)
L-2-amino-3-(indole-3-yl)propionic acid
Family or group:
Amino acids
Indications
Scoring methodology
EFSA approval.
Smoking cessation ✪✪✪✪✪
Daily tryptophan supplementation (50 mg/kg) for 2 weeks helps facilitate smoking cessation.
Posologie
Oral
50 mg/kg
2 - weeks
Premenstrual syndrome ✪✪✪✪✪
According to one study, taking L-tryptophan would reduce 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 characterized primarily by psychiatric symptoms) improves irritability, tension and mood lability. A dose of 6 grams per day was used for 17 days of the cycle, from ovulation until the third day of menstruation, during three consecutive cycles.
Posologie
Oral
6 g
Depression ✪✪✪✪✪
Studies suggest that L-tryptophan may improve the effectiveness of conventional antidepressants.
Posologie
Oral
300 mg
28 - days
Gastric ulcer ✪✪✪✪✪
Clinical research shows that taking 250 mg of L-tryptophan twice daily in combination with 20 mg of omeprazole twice daily for 21 days improves the healing rates of ulcers compared with omeprazole alone in people with Helicobacter pylori 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 people with insomnia. Other clinical research shows that taking 500 mg of L-tryptophan twice daily for 2 weeks may also improve insomnia related to drug withdrawal, such as 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-tryptophan
Sleep-inducing effect of L-tryptophan
Sports performance ✪✪✪✪✪
Some clinical research shows that taking 300 mg of nnL-tryptophan orally with a sweet, electrolyte-rich drink twice a day for 3 days before exercise and on the day of exercise improves power during the last 20 minutes of exercise, compared with taking the drink alone.nn
Posologie
Oral administration
300 mg
4 days
Properties
Essential
L-tryptophan is an essential proteinogenic amino acid. In addition to its proteinogenic role, tryptophan is used in two important metabolic pathways: • The tryptophan pyrrolase pathway leads to the synthesis of niacin (vitamin B3). In practice, it is estimated that two-thirds of the net need for niacin is covered by tryptophan metabolism via this pathway and that the remaining one-third must be provided in the diet as 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 that induces contraction of smooth muscle. Serotonin can be catabolized by monoamine oxidase or converted into melatonin by acetylation followed by methylation. Melatonin is a neurohormone involved notably in the regulation of biological rhythms. Tryptophan is therefore the indispensable precursor of several compounds that are particularly important in the body. The Committee on Toxicity (COT) attached to the Food Standards Agency has set a consumption limit of 220 mg/day for dietary supplements. However, AFSSA estimates the requirements for this amino acid at 4 mg/kg/day.
Sedative
L-tryptophan can cross the blood-brain barrier and be converted into serotonin in the brain, which may explain its sedative effect.
Usages associés
Neurological
Endogenous tryptophan depletion may cause relapse of treated depression or precipitate depressive symptoms in patients with personal or family histories of depression, as well as in healthy subjects. In addition, dietary depletion of L-tryptophan has been associated with relapse of bulimia and with worsening of symptoms of schizophrenia.
Safe dosage
Adults aged 18 and over: 220 mg
The Committee on Toxicity (COT) attached to the Food Standards Agency set the dose of 220 mg/day as the limit for L-tryptophan consumption in food supplements.nnHowever, AFSSA estimates the requirements for this amino acid at nn4 mg/kg/day, i.e. about 200 mg/day.nn
Interactions
Médicaments
Antidepressant: moderate interaction
The combination of a serotonergic antidepressant and nnL-tryptophan could increase the risk of serotonergic side effects, notably cerebral vasoconstrictive disorders.
Benzodiazepines: moderate interaction
The combination of L-tryptophan and benzodiazepines can cause reversible dyskinesias and reversible Parkinsonian-type rigidity.
Central nervous system depressants: strong interaction
Theoretically, the concomitant use of medications that cause sedation can have additive effects when taken with sedative medications. L-tryptophan can cause fatigue and drowsiness. Theoretically, combining L-tryptophan with a sedative medication such as clonazepam, lorazepam, phenobarbital, zolpidem, and others may increase sedation and lead to fatigue and drowsiness.
Contraindications
Pregnant women: contraindicated
Oral intake of L-tryptophan by pregnant women may cause respiratory depression in utero.nn
Breastfeeding: contraindicated
The use of L-tryptophan in breastfeeding women should be avoided due to a lack of reliable information.nn
