What is L-Tryptophan?

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  • Written By: Adrem Siratt
  • Edited By: Heather Bailey
  • Last Modified Date: 07 October 2019
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L-tryptophan is an essential amino acid. The human body is incapable of producing it, so it is necessary for this amino acid to be acquired through food or supplements. L-tryptophan is used by the body to produce several important compounds, such as serotonin, niacin, and melatonin.

L-tryptophan is often used as a supplement. This supplement is used in a variety of different ways, ranging from attention deficit-hyperactivity disorder (ADHD) treatment, depression, and even insomnia. This is thought to primarily be the result of L-tryptophan being converted into 5-hydroxytryptophan (5-HTP), which is then converted into serotonin. Serotonin is a neurotransmitter that is well known as being related to feelings of well being.

Serotonin in the brain binds with serotonin receptors. These receptors are directly related to feelings of happiness. Depression often occurs when the levels of serotonin in the brain drop or when the number of serotonin receptors in the brain decreases. As a result, this enables tryptophan to be used as a treatment for some cases of depression.

Serotonin is a molecule that is unable to pass through the blood-brain barrier. This prevents serotonin in the brain from entering into the body, but it also means that the brain's serotonin levels cannot be increased by ingesting plants rich in serotonin. A metabolic precursor, such as L-tryptophan, must be used instead.


When tryptophan is absorbed by the body, it begins the long process of being converted into the necessary compounds. The body may convert the tryptophan into serotonin. This serotonin is then used by the body in many ways.

The serotonin may then be converted into melatonin in the pineal gland. The production of melatonin is part of the signal the body gives for going to sleep. As a result, it creates a feeling of drowsiness, as well as lowers the temperature of the body. This is why L-tryptophan can be used effectively as a sleep aid for many individuals suffering from insomnia.

In addition to the potential treatments for depression and insomnia, L-tryptophan also can be converted into the essential nutrients known as niacin. Niacin is used by the human body to repair deoxyribonucleic acid (DNA) that has been damaged. Niacin also is used in the production of steroid hormones from within the adrenal gland of the human body. This is yet another reason why tryptophan is an important part of the human body's processes.

L-tryptophan is the primary stereoisomer of tryptophan that is used in the proteins of the body. D-tryptophan is sometimes found in peptides that have been produced naturally. The only difference between these two types is the orientation of the molecule.


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Post 3

I think it's best to get tryptophan from foods. The supplements work for many people but they may also cause side effects. Many people assume that the supplements are safe because tryptophan is a naturally occurring compound. But the doses in supplements may cause side effects.

Turkey has a lot of tryptophan, so does chicken, cheese and milk. Having turkey for dinner and a glass of milk before bed is probably better than taking supplements.

Post 2

@serenesurface-- There may be a medical test for l-tryptophan but I'm not sure how common or available it is. I think many people decide to take l-tryptophan supplements based on their symptoms and with a doctor's recommendation. If you don't eat a wide range of natural, healthy foods like vegetables, fruits, poultry and dairy, you are probably not getting enough l-tryptophan through your diet. Moreover issues like trouble sleeping, anxiety and depression may be signs of low l-tryptophan levels.

But it's best to check with a doctor before trying this supplement anyway.

Post 1

How do I know whether I have an L-tryptophan deficiency and need a supplement? Can anyone take a supplement if they feel it's needed?

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