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.