Using L-Tryptophan to Increase Serotonin Levels for Mood, Sleep & More

Tryptophan is an essential amino acid the body does not produce on its own. It is the main precursor to Serotonin, a chemical and neurotransmitter believed to help regulate sleep, mood, social behavior and cognition.

Type: Amino Acid/Mood Supplement
Used For: Mood Enhancement, Anxiety, Insomnia, Depression, Focus, ADHD, Premenstrual Syndrome (PMS), PMDD, Sleep Apnea, Sleep Disorders, Athletic Performance, Quitting Smoking in conjunction with treatment
Typical Dosage: 500 mg up to 6 grams per day
Drug Interactions: Anti-Depressants, SSRI’s, Benzodiazepines, CNS Depressants, Demerol, Dextromethorphan, MAOI’s, Pentazocine, Phenothiazines, Tramadol
Supplement Interactions: May interact with St. John’s Wort and supplements or herbs with sedative effects or serotonin increasing properties.

What is L-Tryptophan?

L-Tryptophan is considered a Serotonin-boosting supplement with benefits most commonly associated with boosting overall mood, inducing relaxation and a calming feeling, improving sleep quality, controlling appetite and enhancing athletic performance.

Tryptophan Supplement Benefits & UsesTryptophan or L-Tryptophan, its left-handed molecule form more easily synthesized, is one of the 8 essential amino acids the body cannot produce. We can only get it from food sources or by supplementation and it is especially found in high protein foods such as eggs, nuts, turkey, chicken, tuna fish, beans and others.

The body uses L-Tryptophan for protein synthesis and it is a precursor to niacin (also called Vitamin B3) which is made and used by the body to turn carbohydrates, fats and proteins into energy.

L-Tryptophan is also the sole precursor of Serotonin. This natural amino acid is needed to produce this important chemical in the brain thought to be involved in regulating mood, appetite and cognition. It also further synthesizes the hormone Melatonin, involved in regulating sleep-wake cycles.

Low levels of Serotonin have been correlated with anxiousness, panic attacks, depressed mood, insomnia, low energy, poor memory and even binge eating. It is believed that many factors may lead to low levels of this important chemical such as poor diet, hormone changes, prolonged periods of stress, genetics, metabolism and even a lack of sunlight.

Tryptophan is the only natural substance that makes Serotonin and of all amino acids, Tryptophan has the hardest time crossing the blood-brain barrier for conversion into Serotonin since it competes with other amino acids in the blood to enter the brain.

While dietary sources will increase levels of this amino acid, it may not be enough to produce adequate amounts of Serotonin and counteract acute emotional imbalances. In these cases, supplementation may help encourage serotoninergic activity in the brain.

This article will take a look at the benefits of L-tryptophan, how this amino acid works in the body, the potential side effects and safety profile of this supplement.

Benefits of L-Tryptophan For Serotonin Levels

Most of the benefits associated with taking L-Tryptophan supplements is related to this amino acid being the sole natural precursor to brain Serotonin synthesis. Higher levels of Serotonin promote a happier mental state, calmness, restful sleep, appetite control and optimal cognition.

Serotonin is a molecule too large on its own in supplement form to enter the brain which is why a precursor or a reuptake inhibitor is needed to raise its level.

Whether you are getting tryptophan from food sources or supplements, it is broken down in the liver into metabolites such as niacin (Vitamin B3) and 5-HTP (5-hydroxytryptophan) also available as a supplement, which then crosses the blood-brain barrier, enters the brain and is directly converted into Serotonin.

Serotonin is a chemical and neurotransmitter that relays signals between nerve cells and regulates their intensity in the brain. It also regulates blood pressure and plays a role in sleep cycles, appetite (promotes a feeling of fullness), sexual desire, cognition and most significantly in mood and social behavior often referred to as “the happy chemical”.

Mood and Cognition

Low levels of Serotonin have been linked to sleeping problems, symptoms of anxiety and depression, aggression, irritability, short-term memory loss, poor cognition and the tendency to overeat. This is especially true with craving carbohydrates since they, in fact, enhance Serotonin levels by increasing the release of insulin that helps to facilitate the transport of Tryptophan which often can lead to elevating mood.

Negative and anxious thoughts, agitated emotions, compulsiveness and binge eating may be calmed when Serotonin levels are balanced, helping to better manage general stress triggers.

Additionally, cognition and mental focus are improved when distractions are reduced. Reviews of Tryptophan supplements suggest it is used as a remedy for mild depression, stress, anxiety and all sorts of mood imbalances and users claim it helps promote relaxation, stress relief and improves sociability.

Sleep Patterns

L-Tryptophan supplements are commonly used by people suffering from insomnia to help promote better sleep patterns. An inability to regulate your emotions make you more prone to insomnia and the precursor to Melatonin, the main hormone that promotes sleep and linked to regulating sleep cycles is Serotonin which is derived from the amino acid Tryptophan.

Melatonin is a natural hormone most notably involved in maintaining proper sleep-wake cycles (the circadian rhythm) or our internal clock that is responsible for healthy sleep cycles.

During the day, Serotonin synthesis is high (depending on how long and how much sunlight you are exposed to) and at night when light levels drop, Serotonin converts into Melatonin at higher levels. Taking Tryptophan at night, especially with a carbohydrate snack may help enhance its uptake into the brain.

Exercise Performance

Serotonin is also thought to decrease sensitivity to pain. Serotonergic drugs are commonly used to treat migraines and serotonin-norepinephrine reuptake inhibitors have been used to help with pain associated with fibromyalgia.

Tryptophan supplementation has shown to significantly increase beta-endorphin release. Endorphins are naturally produced by the body in response to pain but also triggered by exercise. A study showed an increase in exercise time in participants by over 49% which may be due to an increase in pain tolerance and may why this supplement is often used to boost athletic performance.

Research on the effects of L-Tryptophan for any conditions such as anxiety, depression, insomnia, pain is limited and more clinical trials are needed. While this compound is a prescription medication in a few countries, in the USA it is not approved by the FDA to prevent or treat any conditions.

Using Tryptophan vs 5-HTP to Boost Serotonin

There are many available Tryptophan supplements but many people wonder whether taking this compound in the form of 5-HTP which is an important byproduct of Tryptophan and intermediate step to boosting Serotonin levels, is more effective.

Both 5-HTP and L-Tryptophan use the same pathways to increase the amount of Serotonin but they aren’t the same. Tryptophan is an essential amino acid found in food sources as opposed to 5-HTP which can only be added to the diet in supplement form.

5-HTP is a precursor to Serotonin and synthesized directly from Tryptophan in the body through the action of the enzyme tryptophan hydroxylase. Both these supplements are believed to produce almost identical effects, however, the effects of 5-HTP are said to be much faster acting and more potent since one step in the conversion process to serotonin is eliminated.

Since Tryptophan requires more digestive processing, it is also believed that taking 5-HTP instead may reduce the occurrence of side effects. User reviews suggest that some people find L-Tryptophan works better for them while others find 5-HTP more effective. Which serotonin boosting supplement you choose is based on individual preference.

The use of 5-HTP as a cure for hangovers has gained a lot of popularity. It is believed that heavy drinking, nicotine and marijuana intake all cause a surge in serotonin release by your neurons but once the temporary highly elated mood fades, it is thought to cause a significant drop in levels of serotonin, lower than your initial level which may account for its reputation for this purpose.

L-Tryptophan Side Effects and Interactions

Tryptophan is found in many food sources and most users taking it in supplement form will typically find this compound easily tolerated and experience few to no side effects when taking it in moderate dosages
(between 500 mg up to 6 grams in total per day), although most do not need to take the higher dosage range.

Some mild and transient side effects have been reported including nausea, heartburn, stomach upset, headaches, drowsiness and loss of appetite. It is a good idea to start with a low dose to first determine how your body reacts to it.

The safety and the appropriate dosage between this range can depend on several factors including age, weight, individual sensitivities and present tryptophan levels in the body. It is always recommended to speak to your doctor first before taking new supplements to determine the proper dosage for your needs.

Warning: Do not take Tryptophan in higher doses than 6 grams per day or combine this supplement or 5-HTP with medications or over the counter drugs that alter serotonin levels in the body. This can lead to Serotonin Syndrome.

This includes anti-depressant medications including SSRI’s and MAOI’s, Dextromethorphan (Robitussin DM and other cough medications), Meperidine (Demerol), Pentazocine (Talwin) and Tramadol (Ultram).

Although rare, Serotonin Syndrome occurs when there is too much Serotonin stimulation. Symptoms include delirium, high fever, excessive sweating, high blood pressure, irregular heartbeat and in severe cases if left untreated it can be fatal.

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  1. Segura R, Ventura JL. Effect of L-tryptophan supplementation on exercise performance. Int J Sports Med. 1988 Oct;9(5):301-5.[source]
  2. Fukuwatari T, Shibata K. Nutritional aspect of tryptophan metabolism. Int J Tryptophan Res. 2013;6(Suppl 1):3-8. Published 2013 Jul 21. doi:10.4137/IJTR.S11588 [source]
  3. Richard DM, Dawes MA, Mathias CW, Acheson A, Hill-Kapturczak N, Dougherty DM. L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications. Int J Tryptophan Res. 2009;2:45-60. [source]
  4. Curzon G. Serotonin and appetite. Ann N Y Acad Sci. 1990;600:521-30; discussion 530-1. [source]
  5. Sapun-Malcolm D, Farah JM Jr, Mueller GP. Serotonin and dopamine independently regulate pituitary beta-endorphin release in vivo. Neuroendocrinology.1986;42(3):191-6. [source]
  6. Jenkins TA, Nguyen JC, Polglaze KE, Bertrand PP. Influence of Tryptophan and Serotonin on Mood and Cognition with a Possible Role of the Gut-Brain Axis. Nutrients. 2016;8(1):56. Published 2016 Jan 20. doi:10.3390/nu8010056 [source]
  7. den Boer JA, Westenberg HG. Behavioral, neuroendocrine, and biochemical effects of 5-hydroxytryptophan administration in panic disorder. Psychiatry Res. 1990 Mar;31(3):267-78.[source]
  8. Maron E, Shlik J, Nutt DJ. Tryptophan research in panic disorder. Int J Tryptophan Res. 2008;1:3-12.[source]
  9. Lindseth G, Helland B, Caspers J. The effects of dietary tryptophan on affective disorders. Arch Psychiatr Nurs. 2014;29(2):102-7.[source]
  10. Cowen PJ, Browning M. What has serotonin to do with depression?. World Psychiatry. 2015;14(2):158-60.[source]
  11. Juhl JH. Fibromyalgia and the serotonin pathway. Altern Med Rev. 1998 Oct;3(5):367-75.[source]
  12. Khaliq S, Haider S, Ahmed SP, Perveen T, Haleem DJ. Relationship of brain tryptophan and serotonin in improving cognitive performance in rats. Pak J Pharm Sci. 2006 Jan;19(1):11-5.[source]
  13. Watts SW, Morrison SF, Davis RP, Barman SM. Serotonin and blood pressure regulation. Pharmacol Rev. 2012;64(2):359-88.[source]
  14. Palego L, Betti L, Rossi A, Giannaccini G. Tryptophan Biochemistry: Structural, Nutritional, Metabolic, and Medical Aspects in Humans. J Amino Acids. 2016;2016:8952520.[source]
  15. Fernstrom JD. Effects and side effects associated with the non-nutritional use of tryptophan by humans. J Nutr. 2012 Dec;142(12):2236S-2244S. doi: 10.3945/jn.111.157065. Epub 2012 Oct 17.[source]
  16. Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled clinical trial of L-tryptophan in premenstrual dysphoria. Biol Psychiatry. 1999 Feb 1;45(3):313-20.[source]
  17. DiPalma D, Rezvani AH, Willette B, Wells C, Slade S, Hall BJ, Levin ED. Persistent attenuation of nicotine self-administration in rats by co-administration of chronic nicotine infusion with the dopamine D(1) receptor antagonist SCH-23390 or the serotonin 5-HT(2C) agonist lorcaserin. Pharmacol Biochem Behav. 2018 Nov 9. pii: S0091-3057(18)30398-8. doi: 10.1016/j.pbb.2018.11.002.[source]
  18. Marks DM, Shah MJ, Patkar AA, Masand PS, Park GY, Pae CU. Serotonin-norepinephrine reuptake inhibitors for pain control: premise and promise. Curr Neuropharmacol. 2009;7(4):331-6.[source]
  19. King RB. Pain and tryptophan. J Neurosurg. 1980 Jul;53(1):44-52. PubMed PMID: 6106049.[source]
  20. Dietary supplements and sports performance: amino acids. J Int Soc Sports Nutr. 2005;2(2):63-7. Published 2005 Dec 9. doi:10.1186/1550-2783-2-2-63[source]
  21. Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev. 2002;(1):CD003198.[source]
  22. Hartmann E. Effects of L-tryptophan on sleepiness and on sleep. J Psychiatr Res. 1982-1983;17(2):107-13.[source]
  23. Velenovská M, Fisar Z. Effect of cannabinoids on platelet serotonin uptake. Addict Biol. 2007 Jun;12(2):158-66.[source]
  24. Tollefson GD. Serotonin and alcohol: interrelationships. Psychopathology. 1989;22 Suppl 1:37-48.[source]
  25. Awtry TL, Werling LL. Acute and chronic effects of nicotine on serotonin uptake in prefrontal cortex and hippocampus of rats. Synapse. 2003 Dec 1;50(3):206-11.[source]
  26. Singer S, Rossi S, Verzosa S, Hashim A, Lonow R, Cooper T, Sershen H, Lajtha A. Nicotine-induced changes in neurotransmitter levels in brain areas associated with cognitive function. Neurochem Res. 2004 Sep;29(9):1779-92.[source]
  27. Natural Medicines Comprehensive Database. L-Tryptophan monograph. Accessed Dec 14, 2018[source]
  28. Zagajewski J, Drozdowicz D, Brzozowska I, Hubalewska-Mazgaj M, Stelmaszynska T, Laidler PM, Brzozowski T. Conversion L-tryptophan to melatonin in the gastrointestinal tract: the new high performance liquid chromatography method enabling simultaneous determination of six metabolites of L-tryptophan by native fluorescence and UV-VIS detection. J Physiol Pharmacol. 2012 Dec;63(6):613-21.[source]

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