- Promotes healthy sleep
- Increases mood
- Suppresses appetite
L-Tryptophan is an essential amino-acid found in foods rich in protein, and functions in cellular structure, the nervous system and as a precursor to serotonin, melatonin and niacin. L-Tryptophan supplement is efficient at promoting healthy sleep, increasing mood and suppressing appetite due to its effects on endogenous serotonin and melatonin levels. Recommended dosage of L-Tryptophan supplements is around 3-5grams daily for mood increase, appetite suppression and promotion of healthy sleep. There are very few negative side effects associated with L-Tryptophan supplementation.
L-Tryptophan product reviews
- L-Tryptophan is an essential amino-acid found in foods rich in protein, and functions in cellular structure, the nervous system and as a precursor to serotonin, melatonin and niacin
- L-Tryptophan is efficient at promoting healthy sleep, increasing mood and suppressing appetite due to its effects on endogenous serotonin and melatonin levels
- Recommended dosage of L-Tryptophan supplements is around 3-5grams daily for mood increase, appetite suppression and promotion of healthy sleep (taken before bed)
L-Tryptophan is an essential amino-acid (cannot be biosynthesized by humans) and is a precursor to serotonin and melatonin. Foods that are high in tryptophan include red meat, poultry (like turkey), fish, eggs, legumes and grains. Being an amino-acid, tryptophan plays a vital role in structural processes of our bodies – it is one of the 22 building blocks of all proteins. Its role as a precursor to serotonin, melatonin and niacin are important when examining its effects as a supplement.
L-Tryptophan has been shown to be effective in the promotion of healthy sleep (most likely due to its effect on melatonin levels). Supplements of this amino-acid are also associated with increases in mood and appetite suppression, due to the associated increase in serotonin levels.
L-Tryptophan is coded by the genetic codon UGG and is found in the trp operon in many species of bacteria.
L-Tryptophan effects / benefits
Promotion of healthy sleep
L-Tryptophan is a metabolic precursor to serotonin (via the 5-hydroxtryptophan (5-HTP) intermediate) as well as melatonin. By acting as a precursor to melatonin, L-tryptophan is able to help promote healthy sleep. Melatonin is the brain’s natural sleep aid but melatonin supplements are highly ineffective at crossing the blood-brain barrier. Tryptophan, a simple amino-acid, is able to cross-over into the central nervous system and help promote the body’s process of creating both serotonin and melatonin.
Multiple studies have shown the efficiency of L-Tryptophan supplementation at promoting healthy, restful sleep. It appears to be efficient in lowering the sleep latency time (length of time from full wakefulness to sleep) from the first night of dosage. L-Tryptophan has been shown to help aid sleep over a longer period of time and when used in cycles, known as “interval therapy”.
It is interesting to note that our daily intake of L-Tryptophan supplements from dietary sources ranges from around ½ to 2grams. Even when taking dietary supplements at these low doses, studies have shown improvements in sleep.
Increase in mood
As mentioned above, L-Tryptophan is a precursor to both serotonin and melatonin. Supplementing with L-Tryptophan has been shown to increase serum serotonin and melatonin levels in animal studies.
Serotonin has long been associated with increased mood and happiness. Acute tryptophan depletion (ATD) is associated with irritability and low general mood. Low serotonin has been shown to contribute to low mood and mood swings, but has not been proven to directly cause a low mood on its own. Mood is dependent on many factors, including susceptibility to depression and anxiety, as well as social behaviour.
A recent review on serotonin studies found that while low serotonin levels may not directly cause low moods, higher serotonin levels were definitely associated with better social interactions (less aggressive and more agreeable) in various behavioural studies. Therefore, while evidence is not yet conclusive that serotonin directly increases mood in all people; it can be stated that serotonin does increase positive social behaviour, which contributes to a better mood.
L-Tryptophan directly increases serum serotonin levels and therefore contributes to more agreeable social behaviour and interactions, and directly or indirectly results in an increase in mood.
Many supplements and chemicals that increase levels of serotonin, or inhibit the breakdown of naturally released serotonin are considered effective at lowering appetite. Research has found that higher serum serotonin levels specifically lower the cravings for carbohydrates over other food types.
A recent study on L-Tryptophan supplementation in patients suffering from obesity and eating disorders found a clear correlation between L-Tryptophan and appetite suppression. The study was conducted on 20 obese patients. 10 were administered varying doses of L-Tryptophan (1, 2 and 3g) before a plated meal was served (group 1). The other 10 (group 2) were given lactose placebo.
“The mean ± SD total calorie intakes were: group I 1188 ± 94 (1 g); 1031 ± 93 (2 g: p < 0.05) and 1016 ± 85 (3g: p<0.05); group II: 1294 ± 62. There was a progressive decrease in carbohydrate consumption (expressed as available monosac charide) in function of the tryptophan dose: placebo 131 ± 8 g; one g tryptophan 123 ± 9; two g 114 ± 13; three g 107 ± 10. Protein consumption was less affected.” (Cavaliere and Medeiros-Neto, 2014)
These results show clearly show a significant, dose-dependent decrease in food consumption (specifically carbohydrates) associated with L-Tryptophan supplementation.
L-Tryptophan recommended dosage
Doses of L-Tryptophan have varied from study to study. Some studies on the effects of L-Tryptophan supplements on sleep have found that doses as low as 250mg may help induce healthy sleep when taken before bed. Most studies recommend a dosage of between 3-5 grams daily for producing healthy sleep and appetite suppression effects. Some studies have also used significantly higher doses (from 5-15grams before bed) which may need to be taken in two week “on-off” cycles known as “interval treatment”.
L-Tryptophan side effects / warnings
L-Tryptophan side effects are rare and are generally very subtle if present at all.
WebMD suggests that possible side effects of L-Tryptophan supplements may include heartburn, stomach pain, gas and headache. 
 “Evaluation of L-tryptophan for treatment of insomnia: a review” Schneider-Helmert D, Spinweber CL, Psychopharmacology (Berl). 1986;89(1):1-7
 “Effect of orally administered L-tryptophan on serotonin, melatonin, and the innate immune response in the rat” Esteban S,Nicolaus C, Garmundi A, Rial RV, Rodríguez AB, Ortega E, Ibars CB, Mol Cell Biochem. 2004 Dec;267(1-2):39-46.
 “The effect of raising and lowering tryptophan levels on human mood and social behaviour”, Simon N. Young, Philosophical Transactions B, February 2013 Volume: 370 Issue: 1661
 “The anorectic effect of increasing doses of L-tryptophan in obese patients” Eating and Weight Disorders - Studies on Anorexia, Bulimia and Obesity, December 1997, Volume 2, Issue 4, pp 211-215
 “Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake.” Hartmann E, Spinweber CL, J Nerv Ment Dis. 1979 Aug;167(8):497-9.
 “L-Tryptophan” WebMD.com, retrieved 23-12-2014