Tryptophan is an essential amino acid that serves several important purposes, like nitrogen balance in adults and growth in infants. It also creates niacin, which is essential in creating the neurotransmitter serotonin.

There are two types of tryptophan: L-tryptophan and D-tryptophan. The only difference between the two types is the orientation of the molecule.

You can get tryptophan through certain foods or a supplement in powder form.

Foods with tryptophan

Tryptophan can be found in some foods, especially those high in protein. Foods known to be high in tryptophan include:

  • chicken
  • eggs
  • cheese
  • fish
  • peanuts
  • pumpkin and sesame seeds
  • milk
  • turkey
  • tofu and soy
  • chocolate

In order for tryptophan to be converted into niacin, however, your body needs to have enough iron, vitamin B-6, and vitamin B-2.

Health benefits

There are a number of health benefits from the naturally-occurring tryptophan found in foods. Most of these health benefits come from the potential increase of niacin and thus serotonin. The benefits from more serotonin include:

  • promoting healthier and better quality sleep
  • relief from depression and anxiety
  • increased emotional well-being
  • managing pain tolerance

Used for & Why

L-tryptophan has been used successfully for people with insomnia in many studies,including double-blind trials.
Double-blind research has also shown that oral L-tryptophan can increase tolerance to acute pain.
Premenstrual Syndrome
Some research suggests that L-tryptophan may help balance mood symptoms associated with PMS.
Bipolar Disorder
Supplementation with L-tryptophan has led to improvement in depression in many studies, though its effect on bipolar disorder needs more study.
Several controlled trials have found L-tryptophan as effective as antidepressant medications. Depressed people should consult a doctor before use.
Obsessive-Compulsive Disorder
With a doctor’s supervision, some people with OCD have experienced some symptom relief from supplementing with L-tryptophan.
L-tryptophan supplementation has occasionally been helpful for specific schizophrenia symptoms, such as aggression and memory function.
Seasonal Affective Disorder
Some research suggests that L-tryptophan alone or in combination with light therapy may improve SAD symptoms.
Alcohol Withdrawal (Glutamine, L-Tyrosine, Multivitamin, Phenylalanine)
In double-blind research, alcoholics treated with L-tyrosine combined with DLPA (D,L-phenylalanine), L-glutamine, prescription L-tryptophan, plus a multivitamin had reduced withdrawal symptoms and decreased stress.
Research suggests a connection between anxiety and serotonin deficiency and that its precursur L-tryptophan may help reduce anxiety in people with social anxiety disorder and neurosis.
Attention Deficit–Hyperactivity Disorder
Imbalances in the brain chemical serotonin, or low blood levels of its precursor, L-tryptophan, have been associated with ADHD in some (though not all) studies
Bulimia (Vitamin B6)
Vitamin B6, when taken with L-tryptophan, has been shown to improve eating behavior, feelings about eating, and mood among women with bulimia.
L-tryptophan may be beneficial for people with bulimia, as this amino acid synthesizes serotonin, a hormone that helps regulate food intake and appetite.
The brain chemical serotonin may affect blood pressure regulation, and animal research suggests its precursur L-tryptophan may help prevent and manage hypertension.
Migraine Headache
Preliminary research has found abnormally low levels of serotonin in the brains of people suffering a migraine attack, which was reversed with L-tryptophan supplements.
Animal research and preliminary human reports suggest that serotonin precursors such as L-tryptophan might help control appetite and promote weight loss.
Restless Legs Syndrome
Preliminary research has shown some benefit reducing symptoms of restless legs syndrome and the insomnia that often accompanies it.
Smoking Cessation
In one study, tryptophan supplements along with a high-carbohydrate diet lessened withdrawal symptoms and helped people smoke fewer cigarettes.
Tardive Dyskinesia
Animal research and preliminary human reports suggest that L-tryptophan may help  reduce the severity of symptoms.