Miracon Science

L-Tryptophan

Synonym(s): tryptophan
Nutrient group: Amino acids, Neurotropic agents

Sources and physiological effects

Dietary sources
L-tryptophan is a proteinogenic amino acid, which belongs to the essential amino acids. As such, it cannot be synthesized by the human body itself and must be ingested with food. L-tryptophan does not occur in the diet in its free form, but as a component of proteins and peptides. Good sources of L-tryptophan include soybeans, cashew and sunflower seeds, chicken, beef and veal, and chicken eggs.
Physiological effects
Serotonin metabolism
  • 5-HTP is an intermediate step in the conversion of tryptophan to serotonin.
Hormones and neurotransmitters
  • As precursor of melatonin and serotonin it influences the sleep-wake-rhythm, appetite control, mood, stress tolerance and pain perception.
Energy metabolism
  • Biosynthesis of respiratory chain coenzymes (NAD, NADH).
Development
  • Support of brain maturation and training of sleep and wakefulness.

Recommended intake

Requirement
Increased demand Toddlers, growth, stress, oral contraceptives, high protein meals, inflammatory diseases, fructose intolerance  

 

Recommended intake  

Toddlers

 19 mg/kg bw daily
Adults 3 mg/kg bw daily
Recommended intake according to food labelling regulations
(= 100 % TB marking on label)		  
  N/A
Nutrient safety  
UL Long-term daily intake at which no negative health effects are to be expected

N/A
NOAEL  Maximum intake, with no observed adverse effect


2.32 g/d

 
Highest observed intake (HOI)   N/A

Detailed information

L-tryptophan - essential for serotonin synthesis
L-tryptophan, an essential amino acid, is converted into the neurotransmitter serotonin in the body via the intermediate 5-hydroxy-tryptophan. A tryptophan deficiency, and the resulting reduced serotonin level in the blood serum appears to cause not only depressive moods and mood swings but also pain syndromes, PMS and a lack of appetite control. Through an exogenous supply of L-tryptophan disturbances in neurotransmitter metabolism can be normalized (1).

L-tryptophan also acts on the melatonin level in the body by increasing the serotonin content. The hormone melatonin is produced from serotonin in the epiphysis during the night hours and has a sleep-promoting effect. (2) Sleep disorders often occur together with feelings of depression and are associated with low serotonin/melatonin levels in the body.
The L-tryptophan concentration in the central nervous system (CNS) can be increased by supplementing L-tryptophan with carbohydrates. These cause an increase in insulin levels, through which all other amino acids are increasingly introduced into muscle cells and thus no longer compete with tryptophan for entry into the CNS. (6)
B vitamins and tryptophan, a useful combination
The B vitamins niacin, vitamin B1 and vitamin B6 are indispensable for successful serotonin synthesis, while the combination of L-tryptophan with vitamin B6 and magnesium is recommended for sleep disorders. (1) Niacin also helps with falling asleep and can improve the quality of sleep. (4) For vitamin B6 there are indications that the intensity of dreams and the dream recall increase through supplementation. (5)
Supplementation with tryptophan against sweet craving
Serotonin also plays an important role in eating habits. In controlling food intake, there are a number of neurotransmitters and neuropeptides that regulate selective intake of food components. L-tryptophan as a precursor of serotonin counteracts the absorption of carbohydrates and can reduce overall food intake. (3)
Tryptophan has a positive effect on social behavior
Tryptophan has a positive effect on social behavior and mood. In a double-blind cross-over study the effect of 1g tryptophan 3 times a day on social behavior and mood was examined. The administration of tryptophan significantly reduced aggressive and irritable behavior, increased willingness to discuss, and conflict situations were classified as solvable. Men also showed a reduction in dominant behavior. Thus, the administration of tryptophan showed an improvement in constructive social behavior and an improved assessment of others (7).

Reference values

Parameter Substrate Reference value Description
L-Tryptophan  Serum 34-90 nmol/l Amino acid
L-Tryptophan Urine < 0.9 mg/g Organix-Neuro, ratio tryptophan / L-Kynurenine
Kynurenine/ L-Tryptophan - Ratio  Urine < 0.6 Index   Organix-Neuro, Ratio-Tryptophan- / L-Kynurenine

Deficiency symptoms

Impact on Symptoms
General well-being Headache, concentration problems, low stress tolerance
Eating behavior Preference for sweet (carbohydrate cravings) 
Digestion Obstipation 
Sleeping behavior Problems falling asleep and with quallity of sleep
Psyche Anxiety, aggressiveness, depression 

Administration

General mode of administration
 
When
  • Sleep disorders: L-tryptophan should preferably be taken 30 minutes before bedtime with a carbohydrate-rich drink.
  • For depressive moods, pain syndromes, PMS and to control appetite: L-tryptophan should be taken throughout the day at meal time.
  Notes:
There is the possibility of interaction with antidepressants (monoaminooxidase inhibitors, serotonin reuptake inhibitors, e.g. fluoxetine, fluvoxamine, parexetine) as well as with certain drugs for the treatment of Parkinson's (e.g. selegiline), cancer (procarbazine) and the appetite suppressant dexfenfluramine. When taking these drugs L-tryptophan should not be used additionally.
Side effects
Dizziness, headache, photosensitivity and sedation
Contraindications
Severe liver failure, hepatic encephalopathy, renal insufficiency, pregnancy and lactation, disorders of amino acid metabolism, when taking antidepressants, Parkinson therapeutics and appetite suppressants

Interactions

Drug interactions 
Antidepressants
(tricyclic, lithium)		 The effect of antidepressants is enhanced by L-tryptophan.
Antidepressants
(MAO inhibitor, SSRI)		 Serotonin syndrome possible with simultaneous administration.
Nutrient interactions
Amino acids L-tryptophan, tyrosine, phenylalanine, valine, leucine and isoleucine hinder transport through the blood-brain barrier.

Description and related substances

Description
Proteinogenic, essential, aromatic amino acid
Related substances
L-tryptophan

References

References

1) Gröber, U. 2002. Orthomolekulare Medizin. Ein Leitfaden für Apotheker und Ärzte.
2) Dietl, H., Ohlenschläger, G. 2003. Handbuch der orthomolekularen Medizin. Prävention und Therapie durch körpereigene Substanzen.
3) Lopez-Esparza, S. et al. 2015. Expression of hippocampal serotonin receptors 5-HT2C and 5-HT5A in a rat model of diet-induced obesity supplemented with tryptophan. International Journal of Developmental Neuroscience. 42:80-85.
4) Burgerstein, L. 2002. Handbuch der Nährstoffe.
5) Ebben, M.et al. 2002. Effects of pyridoxine on dreaming: a preliminary study. Percept Mot Skills. 94(1):135-40.
6) Fernstorm, J. D. 1977. Effects of the diet on brain neurotransmitters. Metabolism. 26:207-233
7) Marije aan het Rot. et al. Young. Social behaviour and mood in everyday life: the effects of tryptophan.

References Interactions
Stargrove, M. B. et al. Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies, 1. Auflage. St. Louis, Missouri: Elsevier Health Sciences, 2008.
Gröber, U. Mikronährstoffe: Metabolic Tuning –Prävention –Therapie, 3. Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2011.
Gröber, U. Arzneimittel und Mikronährstoffe: Medikationsorientierte Supplementierung, 3. aktualisierte und erweiterte Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2014.
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