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Supplement Facts & Directions

Supplement Facts

Serving Size: 500 milligrams
Servings Per Container: Varies
Amount Per Serving % Daily Value*
L-Tryptophan 500 mg

* Percent Daily Values are based on a 2,000 calorie diet.
† Daily Value Not Established
‡ These supplement facts may vary from the product you receive. Please call for exact numbers.

Other Ingredients: None


Free of: Soy, Dairy, Yeast, Gluten & Additives.

Directions: As a dietary supplement, take 500 mg (1/2 tsp) up to three times a day or as directed by a physician.

Warning: If you are pregnant, nursing, taking any medications, or have any medical conditions consult your physician before use. It may interact with other medicines, such as anti-depressants. Keep out of reach of children.

Product Details

What is Tryptophan?

Scientists discovered L-Tryptophan in the early 1900s and began synthesizing it in 1949. However, they didn’t perfect the process until the 1980s, which made it possible to obtain useable amounts of tryptophan. It is the L isomer of the essential amino acid tryptophan. The body can’t synthesize essential amino acids, so individuals must consume them through food or dietary supplements.

Meat and dairy products contain the greatest concentration of l-tryptophan, such as milk, tuna, turkey, and chicken. Vegans may have a difficult time obtaining adequate tryptophan from food sources. Prepared oatmeal and walnuts contain a decent amount of tryptophan, but these foods fall short in comparison to meat and dairy sources. Vegans and individuals with dietary restrictions that limit tryptophan intake may benefit from taking tryptophan supplements.

L-Tryptophan easily crosses the blood-brain barrier, and the body uses it to synthesize proteins, serotonin, melatonin, 5-HTP, niacin, and nicotinamide adenine dinucleotide (NAD). It also serves many metabolic functions. A significant amount of research focuses on tryptophan’s involvement in serotonin synthesis. Serotonin has wide-ranging effects in the body, but some of its most important roles include influencing sleep, mood, behavior, and cognition.

Potential L-Tryptophan Benefits

Tryptophan for Sleep

The body produces the sleep hormone melatonin via the tryptophan/serotonin pathway in the brain. Tryptophan supplements boost the availability of melatonin, which may improve sleep in several ways. Studies have shown that tryptophan supplements can reduce the amount of time it takes to fall asleep and increase sleep duration. By increasing melatonin levels, tryptophan may improve sleep quality as well.

Why Does Turkey Make You Sleepy?

Turkey contains high concentrations of tryptophan, which is likely why people feel drowsy after eating a large turkey dinner.

Tryptophan Supplements for Mood

Individuals struggling with low moods often have insufficient levels of tryptophan. Low tryptophan levels can also cause feelings of nervousness, tension, and aggression. Tryptophan supplements may improve social behavior and mood by influencing the availability of serotonin. They may also soother nervous energy and tension.

Tryptophan Supplements for Cognition

Tryptophan may play a role in learning and long-term memory. Individuals with low tryptophan levels often have worse long-term memory compared to individuals with normal levels. Low tryptophan levels can also impair information recall, recognition reaction times, and sensitivity to recognition stimuli.

Other Potential L-Tryptophan Benefits

Tryptophan may provide antioxidant benefits. The body uses tryptophan to synthesize NAD and NAD phosphate (NADP). NAD and NADP are coenzymes that are critical for redox reactions, which involve donating or taking electrons from other molecules. NAD helps protect and repair DNA, and it supports the immune system. As a result, it may improve longevity.

Potential L-Tryptophan Side Effects

As an essential amino acid, tryptophan is generally safe when taken in appropriate doses. Excessive doses can cause dizziness and nausea. Individuals taking medication that increase serotonin should consult their physician before taking tryptophan supplements. Too much serotonin can cause serotonin syndrome, which can be serious.


Tested by Accredited 3rd Party Labs

PureBulk's supplements are tested by accredited third party labs in the USA to ensure their identity, purity and potency. To receive a copy of these test results or any other PureBulk supplement please fill out the COA request form found here.

*NOTE: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

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