Tryptophan

Latest Edit: Hector 2014-03-17 (EDT)

See Also	Amino Acids

Tryptophan is an essential amino acid. It is the precursor to 5-hydroxytrypophan (5-HTP) which is the direct precursor to serotonin. Serotonin is important for mood and sleep; when it is deficient, this can lead to anxiety, depression, insomnia, and various other neuropsychological conditions. Tryptophan is the precursor for vitamin B3 in the form of nicotinamide adenine dinucleotide (NAD). Only about 1/60th of the tryptophan in the body is actually converted to NAD. Pellagra, characterized by the 4 D's, dermatitis, diarrhea, dementia, and death, is both a deficiency in vitamin B3 and tryptophan. Because 5-HTP is the direct precursor to serotonin, it has more clinical applicability.

Article	"The Many Uses of 5-HTP", NMJ, [1], 2011 October

Food Sources

Foods with the highest concentration of Tryptophan include:

• Richest dietary sources: fish, meat, dairy, eggs, nuts, and wheat germ
• Other good sources: the seeds of evening primrose

Tryptophan is the least plentiful amino acid found in foods. It is generally deficient in most dietary protein sources. There may be an increase in carcinogenecity in foods which contain tryptophan which have been charboiled or heated to high temperatures.

Uses

The following are the principle uses of tryptophan .

Article	Dietary tryptophan as a treatment for stress, insomnia and depression, IHP, May 2008

• Depression and Manic-Depressive Mood Swings: Tryptophan is useful with or without other antidepressants such as amine oxidase inhibitors, lithium, and tyrosine. 5-HTP is also useful for treating depression.
• Seasonal affective disorder symptoms generally improve with tryptophan.
• Insomnia: Tryptophan is useful for approximate 50% of people suffering from insomnia. 5-HTP is also useful for treating insomnia.
• Other Conditions: 5-HTP is also useful for treating fibromyalgia, obesity, chronic headache; it relieves pain, relieves fatigue, decreases carbohydrate cravings, enhances sleep quality and REM sleep.

Deficiency Symptoms

• depression
• edema
• hair depigmentation
• insomnia
• lethargy
• liver damage
• muscle loss
• pellagra
• slowed growth in children
• suicidal thoughts
• serotonin deficiency syndrome: nervousness, anxiety, sleep disorders, mood disorders, and excessive appetite

Excess Symptoms

Excess tryptophan or 5-HTP usually in combination with other anti-depressants can cause serotonin syndrome which include signs and symptoms such as:

• agitation
• confusion
• delirium
• tachycardia
• blood pressure changes
• increased sweating

Prescribing Considerations

• Tryptophan is best taken with a low-protein, carbohydrate-rich meal or snack to decrease risk of gastrointestinal distress. Also insulin response to carbohydrates helps to facilitate tryptophan into the CNS.
• No RDA has been established. To determine what your specific requirements are talk to your naturopathic doctor or other trained medical professional.

Safety

• General Adverse Effects: anorexia, dizziness, drowsiness, dry mouth, headache, nausea, sexual disinhibition; over the long-term, tryptophan supplementation may increase levels of other amino acids leading to other adverse side effects
• Children: Insufficient research to determine any age-related effects of taking tryptophan.
• Adults: 7g/150 Ib body weight can lead to gastric irritation, vomiting, head twitching
• Seniors: Insufficient research to determine any age-related effects of taking tryptophan.
• Pregnancy and Breastfeeding: Well designed human studies showing the effects of tryptophan in pregnant and breastfeeding women do not exist. Animal studies show that 8g/day can be teratogenic. It is not known if L-tryptophan passes into breast milk but there have been no reports of adverse effects on nursing babies. Caution should be used.
• Contraindications: achlorhydria, bladder cancer, cataracts, diabetes mellitus, female infertility, pregnancy, psoriasis, sensitivity to L-tryptophan; may exacerbate rheumatoid arthritis
• Precautions: Caution must be used when using tryptophan treatment in combination with other antidepressants; this may lead to serotonin syndrome.

Drug Interactions

Drug interactions include:

Supportive or Beneficial:

• Allopurinol - Co-administration of L-tryptophan and allopurinol may be effective in treating depression, especially refractory cases.
• Lithium - Tryptophan administration may enhance the therapeutic efficacy of lithium and allow for reduced drug effects by enabling lower lithium dose.

Contraindicated:

• Fluoxetine and Related Selective Serotonin Reuptake Inhibitor and Serotonin-Norephinephrine Reuptake Inhibitor (SSRI and SNRI) Antidepressants - Additive effect can result in rapid onset of severe symptoms but might also be applied purposefully within a tightly managed therapeutic protocol. Generally avoid concomitant use. Close supervision with concomitant use.
• Phenelzine and Related Monoamine Oxidase Inhibitors - Concomitant use carries high probability of resulting in clinically significant serotonin excess and major risk of serious adverse effects. Avoid concomitant use.
• Sibutramine and Other Serotonin Agonists - Concomitant use can lead to clinically significant serotonin excess and major risk of serious adverse effects. Avoid concomitant use.

Separate Intake:

• Clorazepate - Potential competition between drug and tryptophan may interfere with drug activity.

Other:

• Tricyclic Antidepressants - Tryptophan can potentiate the action of TCAs. This additive effect can result in rapid onset of severe symptoms but might also be applied purposefully within a tightly managed therapeutic protocol.

Nutrient Interactions

Nutrient interactions include:

• Large, Neutral Amino Acids: Tyrosine, Phenylalanine, Valine, Leucine, Isoleucine - Tryptophan competes with other large amino acids for transport across the blood-brain barrier. Tryptophan is typically administered between meals, with carbohydrates to facilitate entry through the blood-brain barrier and with vitamin B6, vitamin B3, and vitamin C.