L-Tryptophan Dosage for Anxiety and Depression


L-Tryptophan is an essential amino acid found in many foods, especially poultry and other animal meats.

Due to its several metabolic fates, such as being converted to serotonin and melatonin, L-tryptophan has nootropic properties in our body and brain.

Nootropics are a class chemicals that alter brain chemistry to produce a desirable psychological and/or physiological effect (such as improved mood and sense of wellbeing).

What’s particularly unique about L-tryptophan is that is one of few proteinogenic amino acids that has notable nootropic effects.

These nootropic effects are numerous, including: mood enhancement, anxiety reduction, and improved sleep quality.

Despite being found in certain foods, supplementing with free-form L-tryptophan is the most practical, controlled way to reap its nootropic benefits.

Read on as this article goes in depth on how L-tryptophan works, its research-backed benefits, how it may help reduce anxiety, how to dose it, and any potential side effects and safety concerns to be aware of.

Note: the following section details the role of proteinogenic and non-proteinogenic amino acids. L-tryptophan plays a role in protein synthesis in the body which has many of its own benefits; however, this article is going to focus primarily on its nootropic benefits (i.e. actions in our brain).

Pro Hacks:

  • L-tryptophan is one of nature’s few amino acids that is proven to enhance mood, reduce anxiety and improve sleep quality.
  • For reducing anxiety and improving well-being, start with 500mg of supplemental L-tryptophan per day.
  • Try taking L-tryptophanabout one hour before going to bed for a better night’s rest.
  • Despite L-tryptophan being found in certain foods, such as turkey, it is more efficient to supplement with it.
  • L-Tryptophan is just one of many over the counter supplements that can help your anxiety, to find out about others get our free Anxiety Supplement Guide by clicking the button below!

Proteinogenic vs. Non-proteinogenic Amino Acids

Humans utilize 21 proteinogenic amino acids to create specific proteins and hormones that we need to function.

These amino acids are essential for repairing tissue, especially in muscles, bones, skin and hair.

They also play a vital role in organs, glands, arteries, and the 11 body systems.

Of these 21 amino acids, nine are considered essential (L-tryptophan is one), as our body cannot make them on its own and therefore we must obtain them through diet.

The remaining 12 amino acids are considered non-essential and/or conditionally essential since they can be synthesized by our body.

Aside from the 21 amino acids encoded for by our genes and utilized in protein synthesis, there are 100s of amino acids that humans utilize physiologically for other purposes (such as neurotransmission, metabolism, etc.)

These amino acids are considered non-proteinogenic and include key hormones and neurotransmitters such as GABA, L-Theanine, L-Dopa.

Refer to the table below for a list of all the essential and nonessential proteinogenic amino acids (note that selenocysteine is considered a nonessential amino acid but is not listed).



How L-Tryptophan Works

L-tryptophan has a variety of metabolic fates in the body (see the diagram below for reference). One of those fates is being sent to the brain for conversion to 5-HTP , then into serotonin — a neurotransmitter that promotes calmness and relaxation.

Thus, most of L-tryptophan’s nootropic effects are mediated by increased serotonin production, which may then be converted into melatonin.


5 HTP Metabolic Fates

Melatonin is a hormone secreted by the pineal gland in the brain that is used by the body to help regulate its internal body clock and induce sleep.

Exposure to light environments (such as outside during daylight or the bright screen of your smartphone) suppresses melatonin synthesis while being in dark environments does the opposite.

This is why normal circadian rhythms are imperative for proper melatonin production and a healthy sleep cycle.

Therefore, over-the-counter L-tryptophan should be used cautiously with any prescription medications that alter serotonin and/or melatonin levels, such as selective serotonin-reuptake inhibitors (SSRIs).

Ideally, have a licensed healthcare practitioner oversee your L-tryptophan use.

What Determines L-Tryptophan’s Metabolic Fate?

You may be wondering how the body determines which pathway L-tryptophan ultimately proceeds down after ingestion.

Research suggests that the main determinant of whether or not L-tryptophan goes to the brain for conversion to serotonin is its plasma ratio in comparison to other plasma neutral amino acids (since they compete with it for uptake into the brain).[1]

The main competing amino acids include: tyrosine, phenylalanine, leucine, isoleucine, and valine.

The typical Western diet is only estimated to provide roughly 3 to 4 grams of L-tryptophan per day, which is quite minimal in comparison to the aforementioned neutral amino acids.

Thus, when you consume large amounts of protein via diet, much of the L-tryptophan doesn’t go to the brain since it’s typically lower in plasma concentration than these competing amino acids.

Instead, plasma L-tryptophan increases and it is incorporated into proteins.

Benefits of L-Tryptophan Supplementation

L-tryptophan supplements can help treat a variety of conditions, such as anxiety, depression, and insomnia by increasing serotonin levels in the brain.

Furthermore, L-tryptophan supplementation appears to have ramifications on body weight (stemming largely from increased serotonin production).[2]

Serotonin is one of the two primary neurotransmitters involved in feeding patterns and hunger regulation.

In fact, one study precisely characterized the brain sites and receptors involved, as well as the possible physiological role of serotonin, in controlling natural patterns of eating and food selection.[3]

In particular, serotonin’s action is believed to influence both the energy balance and the circadian patterns of eating by activating satiety neurons localized in the hypothalamus.[4]

In simpler terms, serotonin helps relay the signal to your brain that you’re getting full.

In this process, serotonin appears to counteract norepinephrine/noradrenaline and its receptors, which typically induces feelings of hunger.

While serotonin appears to regulate appetite signaling, research suggests that it also plays an important role in macronutrient selection (particularly in obese people consuming large amounts of sugar-laden food).[5]

Thus, it’s not surprising that supplementation with L-tryptophan has been reported to control food intake and reduce body weight in obese patients.4

Below are some of the most relevant research-backed benefits derived from L-tryptophan supplementation:

  • Natural anxiety-reducing properties
  • Stimulates deeper sleep
  • Enhances mood
  • Appears to promote weight loss
  • May treat migraine headaches
  • May alleviate pains associated with fibromyalgia

Notably, scientific research suggests that over-the-counter L-tryptophan may be as effective as several pharmaceutical antidepressants, such as SSRIs, although without the harsh side effects and possible development of dependency that may come from use of such drugs.[6]

Also, individuals with excessive amounts of body inflammation may benefit from L-tryptophan supplementation as their serotonin levels are typically low.

However, it’s not advised to use L-tryptophan supplements before operating a motor vehicle or performing any other activity that requires you to be alert and wakeful.

All this being said, given the importance of proper rest and recovery for health and longevity, many individuals stand to benefit by supplementing with L-tryptophan (especially if you are prone to anxiety and mood disorders).

L-Tryptophan Dosage Recommendations

The amount of L-tryptophan you should supplement with will depend on the purpose for which you want to use it.

For example, research suggests that more L-tryptophan is needed to treat things like obesity as opposed to the amount needed for better sleep. Therefore, the dosage suggestions are as follows: 1,[7],[8]

General Relaxation and Anxiety Reduction: 500-1000mg daily

Better Sleep: 250mg roughly one hour before bed (work steadily up to 1000mg if lower doses are not effective)

Weight Loss: 1000 to 3000mg daily (taken prior to meals)

Pain Associated with Fibromyalgia and Migraine Headaches: 300mg as needed for pain relief (do not exceed 5000mg per day)

When to Take L-Tryptophan

Preferably, always try and take L-tryptophan on an empty stomach (unless otherwise noted above).

If you are taking more than 500mg of L-tryptophan for purposes other than weight loss, it is ideal to split the doses up throughout the day.

So for example, if using 750mg of L-tryptophan per day for anxiety relief, it would be wise to take 250mg at three different times.

However, if you’re using L-tryptophan for better sleep, it is preferable to take your dose about one hour before bed.

Possible Side Effects and Cautions

Most users will tolerate L-tryptophan well with minimal side effects. However, as with most other over-the-counter nootropics, some users may experience various side effects, such as:

  • Dizziness/nausea/vertigo
  • Absence of menstrual bleeding
  • Increased blood cortisol or kynurenine
  • Hypotension and/or hypocholesterolemia
  • Psychic hyperkinetic syndrome
  • Eosinophilia myalgia syndrome (EMS)

Stop use of L-tryptophan supplements should any of these unwanted side effects occur. You may then want to start over with a lower dose or try a different nootropic if the side effects persist.

Take-Home Points

Over-the-counter L-tryptophan supplements present a solid nootropic option with a multitude of benefits stemming from this amino acid’s ability to raise serotonin (and melatonin) levels.

The most applicable benefits of L-tryptophan supplementation include reduction of anxiety, weight loss, and better sleep.

In fact, research suggests L-tryptophan could potentially replace the use of SSRIs and similar drugs for fighting mood disorders, making it particularly useful if you are prone to high anxiety.

However, some individuals will need to experiment with their dose of L-tryptophan to find out what works best for anxiety reduction (start with 500mg per day assess your response).

When comparing L-tryptophan to other nootropics, its major advantages are that it’s well-researched, readily for sale over-the-counter, affordable, and generally free from side effects.

That being said, remember to consult with your healthcare practitioner before adding/substituting L-tryptophan supplements into your regimen (especially if you use drugs that alter serotonin levels).


[1] Fernstrom, J. D., & Wurtman, R. J. (1972). Brain serotonin content: physiological regulation by plasma neutral amino acids. Science, 178(4059), 414-416.
[2] Hrboticky, N., Leiter, L. A., & Anderson, G. H. (1985). Effects of L-tryptophan on short term food intake in lean men. Nutrition Research5(6), 595-607.
[3] Perez-Cruet I, Tagliamonte A, Tagliamonte P, Gessa GL. Changes in brain serotonin metabolism associated with fasting and satiation in rats. Life Sci 1972;1 1:31-9.
[4] Cangiano, C., Ceci, F., Cascino, A., Del Ben, M., Laviano, A., Muscaritoli, M., … & Rossi-Fanelli, F. (1992). Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan. The American journal of clinical nutrition56(5), 863-867
[5] Heraief, E., Burckhardt, P., Wurtman, J. J., & Wurtman, R. J. (1985). Tryptophan administration may enhance weight loss by some moderately obese patients on a protein‐sparing modified fast (PSMF) diet. International Journal of Eating Disorders, 4(3), 281-292.
[6] Williams, J. W., Mulrow, C. D., Chiquette, E., Noël, P. H., Aguilar, C., & Cornell, J. (2000). A systematic review of newer pharmacotherapies for depression in adults: evidence report summary: clinical guideline, part 2. Annals of internal medicine, 132(9), 743-756.
[7] Thomson, J., Rankin, H., Ashcroft, G. W., Yates, C. M., McQueen, J. K., & Cummings, S. W. (1982). The treatment of depression in general practice: a comparison of L-tryptophan, amitriptyline, and a combination of L-tryptophan and amitriptyline with placebo. Psychological medicine, 12(04), 741-751.
[8] HARTMANN, E., & SPINWEBER, C. L. (1979). BRIEF COMMUNICATION: Sleep Induced by L-Tryptophan: Effect of Dosages within the Normal Dietary Intake. The Journal of nervous and mental disease, 167(8), 497-499.



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