What is tryptophan?
Tryptophan (L-tryptophan) is an essential amino acid – i.e. a protein building block that the body cannot produce itself and must therefore take in through the diet. It is important for a whole range of vital processes.
Tryptophan, for example, is not only involved in building proteins. It is also an important precursor of the nerve messenger serotonin, the hormone melatonin and vitamin B3 (niacin).
How much tryptophan daily?
How does tryptophan work?
Tryptophan is absorbed into the blood in the intestine. A small amount passes the blood-brain barrier and enters the central nervous system (brain and spinal cord). There, the amino acid is gradually converted to serotonin and partially further to melatonin.
Most of the tryptophan absorbed in the intestine enters the liver with the blood and is metabolized there. Niacin (vitamin B3) is formed in the process.
Meaning of serotonin
- the body’s own sleep-wake rhythm
- our mood and state of mind
- appetite
- the sensation of pain
- the body temperature
Disturbances in serotonin metabolism are associated with depression, anxiety and sleep disorders. The supplementary supply of tryptophan can help to normalize the disturbed serotonin balance.
Meaning of melatonin
Melatonin, produced from tryptophan via serotonin, is known as the “sleep hormone”. It regulates the day-night rhythm. Specifically, it is formed and secreted at night.
Light inhibits the formation and secretion of melatonin.
Meaning of niacin
Niacin deficiency can lead to the disease pellagra in the long term. Its hallmarks include weakness, lack of appetite and digestive problems, and later also diarrhea, dermatitis (inflammatory skin disease), depression and dementia.
The human body forms about one milligram of niacin from 60 milligrams of tryptophan.
What foods contain tryptophan?
The tryptophan content of selected foods can be found in the following table:
|
Food |
Tryptophan content per 100g |
|
Emmental cheese |
460 mg |
|
Soybeans |
450 mg |
|
Cashew nuts |
450 mg |
|
Peanuts |
320 mg |
|
Chicken |
310 mg |
|
Cocoa powder, unsweetened |
293 mg |
|
Egg |
230 mg |
|
Oatmeal |
190 mg |
|
Rice |
90 mg |
|
Corn |
70 mg |
|
Dates |
50 mg |
|
Milk, 3.5% fat |
49 mg |
|
Mushrooms |
24 mg |
|
Potatoes, boiled |
31 mg |
|
Bananas |
18 mg |
What does tryptophan help against?
In Austria and Switzerland, tryptophan is only on the market as a dietary supplement. Such products may not be advertised for a specific area of application (such as sleep disorders).
Instead, only health claims that are on a positive list of the EU or Swiss legislation are generally permitted for food supplements.
Other applications of tryptophan
Sometimes L-tryptophan is used against depression and anxiety disorders. There are also actual indications that the amino acid works better here than preparations without active ingredients (placebos). However, its effectiveness in this area of application has not been clearly proven.
Other areas of application of tryptophan with unproven efficacy are:
- Menopausal symptoms such as hot flashes (effect not proven)
- Irritable bowel syndrome (effect not proven)
- Relief of the thyroid gland (effect not proven)
Physicians also use tryptophan preparations to compensate for a tryptophan deficiency. However, such a deficiency is practically unknown in industrialized countries.
What are the side effects of tryptophan?
There is no reliable information on the frequency of the individual side effects that are possible when taking the amino acid L-tryptophan.
Both blood pressure-lowering and blood pressure-increasing effects have also been observed.
Tryptophan may impair reactions even when used as directed. Affected individuals are then no longer able to safely drive vehicles such as cars or operate machinery. This is especially true if one has also consumed alcohol.
Tryptophan Deficiency and Excess
Both a deficiency of tryptophan and an excess supply can manifest with symptoms.
Symptoms of tryptophan deficiency
Tryptophan deficiency can cause various symptoms, including sleep problems, mood swings, inner restlessness, loss of performance and listlessness.
Tryptophan deficiency can also lead to the above-mentioned disease pellagra via niacin deficiency (see: “How does tryptophan work?”).
These symptoms are very non-specific. Whether they are actually caused by a deficiency of tryptophan can only be clarified with a blood test.
Symptoms of tryptophan excess
If tryptophan is taken in too high a dose, symptoms may develop that correspond to the common side effects (see above).
How to take tryptophan
For tryptophan medications approved in Germany for the treatment of sleep disorders, the dosage is usually one gram of L-tryptophan daily.
It is taken in the evening about half an hour before bedtime. If necessary, the dose can be increased to two grams of tryptophan. However, it should not be increased further.
Adhere to the dosage recommendation of your tryptophan medication!
When should tryptophan not be used?
Tryptophan should generally not be used by:
- hypersensitivity (allergy) to the active ingredient or other components of the drug or dietary supplement
- severe liver, heart, or kidney disease
- carcinoid syndrome (symptoms caused by a specific type of tumor)
- acute alcohol or drug intoxication
- concomitant use of monoamine oxidase (MAO) inhibitors for depression
- concomitant use of phenothiazines (antipsychotic drugs) and benzodiazepines (sleeping pills and tranquilizers)
- concomitant use of dextrometorphan (over-the-counter cough suppressant)
- children and adolescents under 18 years of age (missing data)
These drug interactions may occur with tryptophan
Tryptophan may potentiate the effects of tricyclic antidepressants (such as amitriptyline) and lithium salts (e.g., in bipolar disorder, depression).
Conversely, the effect of L-dopa (used to treat Parkinson’s disease) may be weakened if tryptophan is taken at the same time. This competes with L-dopa for absorption into the brain.
Carbamazepine increases the effect of tryptophan, while phenytoin weakens it. Both active ingredients are used to treat epilepsy.
Serotonin Syndrome
Excess serotonin can cause the potentially fatal serotonin syndrome. It typically involves a combination of three symptoms:
- Fever
- neuromuscular symptoms (tremors, muscle twitching, muscle rigidity, etc.)
- mental symptoms (impaired consciousness, confusion, disorientation, etc.)
In addition to L-tryptophan, these agents include, for example, St. John’s wort (herbal mood enhancer), paroxetine, clomipramine, MAO inhibitors, and other agents for depression.
Tryptophan during pregnancy and lactation
There are insufficient data on the use of tryptophan during pregnancy and lactation. Therefore, pregnant and breastfeeding women should take the active ingredient only after consulting a doctor.
How to obtain tryptophan
Dietary supplements containing tryptophan, as available in Germany, Austria and Switzerland, are sold over-the-counter.