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L-tryptophan is an essential amino acid or protein building block.

What are its health benefits?

L-trypotophan is important for the development and functioning of many organs in the body. The body converts it into 5-hydroxytryptophan (or 5-HTP) and then serotonin, a hormone that helps control mood and sleep.

An L-trypotophan supplement may have the following benefits:

  • Assisting in the relief of symptoms in women with premenstrual dysphoric disorder such as mood swings, tension and irritability
  • Assisting with the management of stopping smoking by increasing effectiveness of conventional treatments
  • Assisting in the management of facial pain and teeth grinding
  • Assisting with the management of insomnia and sleep apnoea
  • It may help improve mood and assist in the management of mental health conditions, including depression, obsessive-compulsive disorder (OCD) and bipolar disorder, but only limited research has been done on this
  • Assisting in the management of seasonal affective disorder (SAD)
  • Aiding athletic performance

Do you have a deficiency?

The body does not make its own supply of L-tryptophan and needs to get it from food and animal sources.

A diet poor in L-trypotophan may lead to symptoms of deficiency, which include dermatitis, certain digestive problems like diarrhoea, and low serotonin levels which can result in symptoms of depression.

Find it in these foods

L-tryptophan is found in meats such as turkey and chicken, as well as:

  • Bananas
  • Cheese, milk and eggs
  • Chocolate
  • Dried dates
  • Oats
  • Pumpkin and sesame seeds
  • Soya and tofu
  • Peanuts and peanut butter

Recommended dietary allowance (RDA)

The RDA for L-tryptophan will vary according to the condition and patient’s health, although a dosage range has not yet been established scientifically. Discuss dosages with your doctor or Clicks pharmacist.


L-tryptophan should not be taken by pregnant and breastfeeding women.

Patients with eosinophilia (a white blood cell disorder) or liver or kidney disease should also not take L-tryptophan supplements.

It also may react with the following medications: antidepressants (SSRIs or MAOIs) and sedatives.

Possible side effects

Possible side effects could include:

  • Heartburn
  • Stomach pain
  • Gas
  • Nausea
  • Vomiting
  • Diarrhoea
  • Loss of appetite
  • Headache, dizziness and lightheadedness
  • Visual blurring
  • Muscle weakness
  • Fatigue
  • Hives
  • Heart palpitations
  • Tremor and sweating

If taken with existing antidepressant medication, a potentially life-threatening condition called serotonin syndrome may occur. Symptoms include muscle spasm, delirium and coma.

Ensure you discuss dietary supplementation with your Clicks pharmacist to avoid the potential for side effects and adverse interactions with medications.

This medicine has not been evaluated by the Medicines Control Council. This medicine is not intended to diagnose, treat, cure or prevent any disease.

The accuracy of this information was checked and approved by Clicks' pharmacist Waheed Abdurahman in September 2015