Pack size: 100 capsules
Serving: 1 capsule
Servings per pack: 100

ShopAmino acids and proteins

Doctor Life

Optimized Singles

L-Tryptophan

Sleep and mood

53,99 zł

500 mg of pure L-tryptophan in a clearly measured serving
Tryptophan without added melatonin, 5-HTP, or herbal blends
A single-ingredient formula that is easy to fit into your routine

Overview

One active ingredient. One capsule daily. L-Tryptophan provides 500 mg of L-tryptophan in a straightforward formula, making it easy to manage your intake without adding melatonin, 5-HTP, or botanical extracts to your routine.

At the heart of the formula / L-Tryptophan

Thoughtful support. Clear purpose.

01500 mg of pure L-tryptophan in a clearly measured serving
02Tryptophan without added melatonin, 5-HTP, or herbal blends
03A single-ingredient formula that is easy to fit into your routine
04500 mg is an amount directly evaluated in a study in healthy volunteers
05One capsule daily for consistent use
06100 capsules provide 100 daily servings
07A pullulan capsule suitable for vegans and vegetarians

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L-Tryptophan

Made for your daily routine.

L-tryptophan is an essential amino acid, meaning it must come from the diet. In addition to building proteins, it participates in pathways that produce serotonin and, subsequently, melatonin. Researchers have studied these roles in sleep, mood, and nervous system function.

The formula provides L-tryptophan as its only active ingredient, making the amount clear and allowing it to be considered separately from other supplements.

The pullulan capsule and absence of animal-derived ingredients make the product suitable for vegans and vegetarians. Each bottle contains 100 capsules, a 100-day supply at one daily.

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L-Tryptophan

Why does L-tryptophan matter?

L-tryptophan is an essential amino acid and a precursor in serotonin production. Serotonin can then be converted into melatonin. Much of the body's tryptophan also follows other routes, including the kynurenine pathway, so intake does not translate directly into a predictable serotonin or melatonin effect.

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L-Tryptophan

What research informs L-Tryptophan?

Human research has examined tryptophan in relation to sleepiness, sleep, and mood. One study used 500 mg and reported changes in subjective sleepiness. A review of 11 mood trials included amounts from 0.14 to 3 g daily, while a sleep meta-analysis examined wakefulness after sleep onset. Results varied by amount and study design and do not establish a treatment for sleep or mood disorders.

Ingredients / Doctor Life

Every ingredient. Clearly explained.

Each ingredient, its form and quantity — in one place.

Serving1 capsule

Ingredient amounts for the servings shown in the table.
Ingredient	1 capsule
L-tryptophan	500 mg

*NRV: Nutrient Reference Value

Full ingredient list

L-tryptophan, capsule shell (bulking agent: pullulan).

How to use

Part of your daily rhythm.

How to use

Take 1 capsule daily with a meal.

Important information

Do not exceed the recommended daily serving. Food supplements should not replace a varied diet. A balanced diet and a healthy lifestyle are recommended. Not intended for use during pregnancy or breastfeeding. Store at room temperature, at or below 25°C, out of reach of young children.

Science & sources

Understand the formula.

L-tryptophan is an essential amino acid and a precursor to serotonin, which the body can then use to synthesize melatonin. Research includes a study using 500 mg of L-tryptophan and broader reviews of randomized trials examining mood and sleep quality.

These publications concern the studied ingredients or formulas. They do not all evaluate the finished Doctor Life product, and research results do not guarantee individual outcomes.

01Diet-induced mood changes in normal populations

P. D. Leathwood, P. Pollet

Journal of Psychiatric Research (1982-1983), 17(2), 147-154. DOI: 10.1016/0022-3956(82)90016-4; PMID: 6764931.

In a double-blind study involving 60 healthy volunteers, 500 mg of tryptophan was among the interventions compared with placebo. This is the amount of L-tryptophan in one capsule. Tryptophan shifted ratings toward greater sleepiness and was rated the most calming of the interventions compared. The publication provides direct human-study context for a 500 mg serving.

Read publication ↗

02A systematic review of the effect of L-tryptophan supplementation on mood and emotional functioning

Asako M. Kikuchi, Aya Tanabe, Yoshihiro Iwahori

Journal of Dietary Supplements (2021), 18(3), 316-333. DOI: 10.1080/19390211.2020.1746725; PMID: 32272859.

A systematic review included 11 randomized trials in healthy adults. Some trials linked tryptophan supplementation with improvements in negative emotions and positive mood. The doses examined ranged from 0.14 to 3 g daily, placing the 500 mg serving in Doctor Life L-Tryptophan within the studied range.

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03The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression

Clarinda N. Sutanto, Wen Wei Loh, Jung Eun Kim

Nutrition Reviews (2022), 80(2), 306-316. DOI: 10.1093/nutrit/nuab027; PMID: 33942088.

A meta-analysis of sleep studies found that tryptophan supplementation may affect time spent awake after falling asleep. Dose-response analysis also showed that dose matters and that results differ across sleep measures. The findings contribute to research on tryptophan and sleep physiology.

Read publication ↗

FAQ / L-Tryptophan

Good questions. Clear answers.

Talk to us ↗

How does the 500 mg serving relate to research?

A double-blind study in 60 healthy adults used 500 mg of tryptophan and reported changes in subjective sleepiness. Other studies used different amounts and outcomes. One capsule supplies 500 mg, but matching a studied amount does not guarantee a particular result.

Is L-tryptophan the same as melatonin?

No. L-tryptophan is an essential amino acid earlier in the pathway: it can be converted into 5-HTP, serotonin, and then melatonin. This product contains L-tryptophan, not melatonin.

How do L-tryptophan and 5-HTP differ?

Tryptophan is an essential dietary amino acid. 5-HTP is a later intermediate in the pathway toward serotonin. Their different positions do not make either universally better. This formula supplies L-tryptophan alone.

Has tryptophan's relationship with sleep been studied?

Yes. Tryptophan is a precursor in the serotonin–melatonin pathway, and human trials have examined sleepiness and sleep measures. Findings vary by amount and study conditions. This supplement is not a sleep medication.

Can I combine L-tryptophan with antidepressants, 5-HTP, or other serotonin-related products?

Do not combine these without advice from your doctor or pharmacist. Tryptophan is a serotonin precursor, and combinations with serotonergic medicines or supplements can cause harmful additive effects.

What happened in the 1989 eosinophilia–myalgia syndrome outbreak?

The 1989 U.S. outbreak was linked to L-tryptophan supplements, with a particularly strong association with material from one manufacturer. Investigations examined contaminants and manufacturing conditions. The history underscores the importance of production controls; it does not establish that every modern tryptophan product is risk-free.

Should I take tryptophan on an empty stomach?

Tryptophan competes with other large neutral amino acids for transport, but that does not justify changing this product's directions. Take one capsule daily with a meal, as specified on the label.

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