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Nutritional Supplement

L-Tryptophan

Also indexed as:Tryptophan

L-Tryptophan is an essential amino acid that the body requires to synthesize proteins and specialized molecules such as the neurotransmitter serotonin. Serotonin appears to play significant roles in sleep, emotional moods, pain control, inflammation, intestinal peristalsis, and other body functions.1

References

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25. Demisch K, Bauer J, Georgi K, Demisch L. Treatment of severe chronic insomnia with L-tryptophan: results of a double-blind cross-over study. Pharmacopsychiatry. 1987;20:242-4.

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28. Spinweber CL, Ursin R, Hilbert RP, Hilderbrand RL. L-tryptophan: effects on daytime sleep latency and the waking EEG. Electroencephalogr Clin Neurophysiol 1983;55:652-61.

29. Hartmann E, Lindsley JG, Spinweber C. Chronic insomnia: effects of tryptophan, flurazepam, secobarbital, and placebo. Psychopharmacology (Berl) 1983;80:138-42.

30. Yogman MW, Zeisel SH. Diet and sleep patterns in newborn infants. N Engl J Med 1983;309:1147-9.

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33. Fernstrom JD, Faller DV. Neutral amino acids in the brain: Changes in response to food ingestion. J Neurochem 1978;30:1531-8.

34. Puttini PS, Caruso I. Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study. J Int Med Res 1992;20:182-9.

35. Bruni O, Ferri R, Miano S, Verrillo E. L-5-Hydroxytryptophan treatment of sleep terrors in children. Eur J Pediatr 2004;163:402-7.

36. Kimball RW, Friedman AP, Vallejo E. Effect of serotonin in migraine patients. Neurology 1960;10:107-11.

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39. Menkes DB, Coates DC, Fawcett JP. Acute tryptophan depletion aggravates premenstrual syndrome. J Affect Disord 1994;32:37-44.

40. Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled clinical trial of L-tryptophan in premenstrual dysphoria. Biol Psychiatry 1999;45:313-20.

41. Steinberg S, Annable L, Young SN, Belanger MC. Tryptophan in the treatment of late luteal phase dysphoric disorder: a pilot study. J Psychiatry Neurosci 1994;19 :114-9.

42. Kaye WH, Weltzin TE. Serotonin activity in anorexia and bulimia nervosa: relationship to the modulation of feeding and mood. J Clin Psychiatry 1991;52 Suppl:41-8 [review].

43. Smith KA, Fairburn CG, Cowen PJ. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Arch Gen Psychiatry 1999;56:171-6.

44. Weltzin TE, Fernstrom MH, Fernstrom JD, et al. Acute tryptophan depletion and increased food intake and irritability in bulimia nervosa. Am J Psychiatry 1995;152:1668-71.

45. Oldman AD, Walsh AES, Salkovskis P, et al. Biochemical and behavioural effects of acute tryptophan depletion in abstinent bulimic subjects: a pilot study. Psychol Med 1995;25:995-1001.

46. Anderson IM, Parry-Billings M, Newsholme EA, et al. Dieting reduces plasma tryptophan and alters brain 5-HT function in women. Psychol Med 1990;20:785-91.

47. Mira M, Abraham S. L-tryptophan as an adjunct to treatment of bulimia nervosa. Lancet 1989;ii:1162-3 [letter].

48. Krahn D, Mitchell J. Use of L-tryptophan in treating bulimia. Am J Psychiatry 1985;142:1130 [letter].

49. Brewerton TD, Murphy DL, Jimerson DC. Testmeal responses following m-chlorophenylpiperazine and L-tryptophan in bulimics and controls. Neuropsychopharmacology 1994;11:63-71.

50. Thibault L, Roberge AG. The nutritional status of subjects with anorexia nervosa. Int J Vitam Nutr Res 1987;57:447-52.

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53. Rock CL, Vasantharajan S. Vitamin status of eating disorder patients: relationship to clinical indices and effect of treatment. Int J Eat Disord 1995;18:257-62.

54. Langan SM, Farrell PM. Vitamin E, vitamin A and essential fatty acid status of patients hospitalized for anorexia nervosa. Am J Clin Nutr 1985;41:1054-60.

55. Kaye WH, Weltzin TE. Serotonin activity in anorexia and bulimia nervosa: relationship to the modulation of feeding and mood. J Clin Psychiatry 1991;52 Suppl:41-8 [review].

56. Smith KA, Fairburn CG, Cowen PJ. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Arch Gen Psychiatry 1999;56:171-6.

57. Weltzin TE, Fernstrom MH, Fernstrom JD, et al. Acute tryptophan depletion and increased food intake and irritability in bulimia nervosa. Am J Psychiatry 1995;152:1668-71.

58. Oldman AD, Walsh AES, Salkovskis P, et al. Biochemical and behavioural effects of acute tryptophan depletion in abstinent bulimic subjects: a pilot study. Psychol Med 1995;25:995-1001.

59. Anderson IM, Parry-Billings M, Newsholme EA, et al. Dieting reduces plasma tryptophan and alters brain 5-HT function in women. Psychol Med 1990;20:785-91.

60. Mira M, Abraham S. L-tryptophan as an adjunct to treatment of bulimia nervosa. Lancet 1989;ii:1162-3 [letter].

61. Krahn D, Mitchell J. Use of L-tryptophan in treating bulimia. Am J Psychiatry 1985;142:1130 [letter].

62. Brewerton TD, Murphy DL, Jimerson DC. Testmeal responses following m-chlorophenylpiperazine and L-tryptophan in bulimics and controls. Neuropsychopharmacology 1994;11:63-71.

63. Menkes DB, Coates DC, Fawcett JP. Acute tryptophan depletion aggravates premenstrual syndrome. J Affect Disord 1994;32:37-44.

64. Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled clinical trial of L-tryptophan in premenstrual dysphoria. Biol Psychiatry 1999;45:313-20.

65. Steinberg S, Annable L, Young SN, Belanger MC. Tryptophan in the treatment of late luteal phase dysphoric disorder: a pilot study. J Psychiatry Neurosci 1994;19 :114-9.

66. Stockmeier CA: Neurobiology of serotonin in depression and suicide. Ann N Y Acad Sci 1997, 836:220-32.

67. Eccleston D. L-tryptophan and depressive illness: a valuable adjunct to therapy? Psychiatric Bulletin 1993;17:223-4 [review].

68. Young SN, Teff KL. Tryptophan availability, 5HT synthesis and 5HT function. Prog Neuropsychopharmacol Biol Psychiat 1989;13:373—9.

69. Werbach MR. Nutritional influences on mental illness, 2nd ed. Tarzana, CA: Third Line Press, 1999, 266-67 [review].

70. Buist R: The therapeutic predictability of tryptophan and tyrosine in the treatment of depression. Int J Clin Nutr Rev 1983;3:1-3 [review].

71. Lindberg D, Ahlfors UG, Dencker SJ, et al. Symptom reduction in depression after treatment with L-tryptophan or imipramine. Item analysis of Hamilton rating scale for depression. Acta Psychiatr Scand 1979;60:287-94.

72. Young SN. The clinical psychopharmacology of tryptophan. In Wurtman RJ, Wurtman JJ, eds. Nutrition and the Brain, Volume 7. New York: Raven Press, 1986, 49-88.

73. Thomson J, Rankin H, Ashcroft GW, et al.The treatment of depression in general practice: a comparison of L-tryptophan, amitriptyline, and a combination of L-tryptophan and amitriptyline with placebo. Psychol Med 1982;12:741-51.

74. Bennie E. Mianserin hydrochloride and Ltryptophan compared in depressive illness. Br J Clin Soc Psych 1982;1:90-1.

75. Jaffe G, Grimshaw J. A placebo-controlled comparison of L-tryptophan and amitriptyline in the treatment of depressive illness in general practice. Br J Clin Soc Psych 1985;3:51-5.

76. Cooper AJ, Datta SR. A placebo controlled evaluation of L-tryptophan in depression in the elderly. Can J Psychiatry 1980;25:386-90.

77. Young SN, Chouinard G, Annable L. Tryptophan in the treatment of depression. Adv Exp Med Biol 1981;133:727-37 [review].

78. Angst J, Woggon B, Schoepf J. The treatment of depression with L-5-hydroxytryptophan versus imipramine. Results of two open and one double-blind study. Arch Psychiatr Nervenkr 1977;224:175-86.

79. Nolen WA, van de Putte JJ, Dijken WA, et al. Treatment strategy in depression. II. MAO inhibitors in depression resistant to cyclic antidepressants: two controlled crossover studies with tranylcypromine versus L-5-hydroxytryptophan and nimifensine. Acta Psychiatr Scand 1988;78:676-83.

80. Nolen WA, van de Putte JJ, Dijken WA, Kamp JS. L-5-HTP in depression resistant to re-uptake inhibitors. An open comparative study with tranylcypromine. Br J Psychiatry 1985;147:16-22.

81. D'Elia G, Hanson L, Raotma H. L-tryptophan and 5-hydroxytryptophan in the treatment of depression. A review. Acta Psychiatr Scand 1978;57:239-52 [review].

82. Van Praag HM, Lemus C. Monoamine precursors in the treatment of psychiatric disorders. Nutrition and the Brain, vol. 7, RJ Wurtman, JJ Wurtman, eds. New York: Raven Press, 1986 [review].

83. Van Praag H, de Hann S. Depression vulnerability and 5-hydroxytryptophan prophylaxis. Psychiatry Res 1980;3:75-83.

84. Neumeister A, Konstantinidis A, Praschak-Rieder N, et al. Monoaminergic function in the pathogenesis of seasonal affective disorder. Int J Neuropsychopharmacol 2001;4:409-20.

85. Van der Does AJ. The effects of tryptophan depletion on mood and psychiatric symptoms. J Affect Disord 2001;64:107-19.

86. Levitt AJ, Brown GM, Kennedy SH, Stern K. Tryptophan treatment and melatonin response in a patient with seasonal affective disorder. J Clin Psychopharmacol 1991;11:74-5.

87. Lam RW, Levitan RD, Tam EM, et al. L-tryptophan augmentation of light therapy in patients with seasonal affective disorder. Can J Psychiatry 1997;42:303-6.

88. Ghadirian AM, Murphy BE, Gendron MJ. Efficacy of light versus tryptophan therapy in seasonal affective disorder. J Affect Disord 1998;50:23-7.

89. McGrath RE, Buckwald B, Resnick EV. The effect of L-tryptophan on seasonal affective disorder. J Clin Psychiatry 1990;51:162-3.

90. Birdsall TC. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Alternative Med Rev 1998;3:271-80.

91. Iversen SD. 5-HT and anxiety. Neuropharmacology 1984;23:1553-60 [review].

92. Schruers K, Klaassen T, Pols H, et al. Effects of tryptophan depletion on carbon dioxide provoked panic in panic disorder patients. Psychiatry Res 2000;93:179-87.

93. Argyropoulos SV, Hood SD, Adrover M, et al. Tryptophan depletion reverses the therapeutic effect of selective serotonin reuptake inhibitors in social anxiety disorder. Biol Psychiatry 2004;56:503-9.

94. Hudson C, Hudson S, MacKenzie J. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Can J Physiol Pharmacol 2007;85:928-32.

95. Zang DX. A self body double blind clinical study of L-tryptophan and placebo in treated neurosis. Zhonghua Shen Jing Jing Shen Ke Za Zhi 1991;24:77-80,123-4 [in Chinese].

96. Galligan JJ. Beneficial actions of microbiota-derived tryptophan metabolites. Neurogastroenterol Motil 2018 02;30(2).

97. Namkung J, Kim H, Park S. Peripheral Serotonin: a New Player in Systemic Energy Homeostasis. Mol Cells 2015 Dec;38(12):1023–8.

98. Strasser B, Berger K, Fuchs D. Effects of a caloric restriction weight loss diet on tryptophan metabolism and inflammatory biomarkers in overweight adults. Eur J Nutr 2015 Feb;54(1):101–7.

99. Hrboticky N, Leiter L, Anderson G. Effects of L-tryptophan on short term food intake in lean men. Nutr Res 1985;5:595–607.

100. Cavaliere H, Medeiros-Neto G. The anorectic effect of increasing doses of L-tryptophan in obese patients. Eat Weight Disord 1997;2:211-5.

101. Strain GW, Strain JJ, Zumoff B. L-tryptophan does not increase weight loss in carbohydrate-craving obese subjects. Int J Obes 1985;9:375-80.

102. Comings DE. Serotonin and the biochemical genetics of alcoholism: lessons from studies of attention deficit hyperactivity disorder (ADHD) and Tourette syndrome. Alcohol Alcohol Suppl 1993;2:237-41 [review].

103. Ferguson HB, Pappas BA, Trites RL, et al. Plasma free and total tryptophan, blood serotonin, and the hyperactivity syndrome: no evidence for the serotonin deficiency hypothesis. Biol Psychiatry. 1981;16:231-8.

104. Stadler C, Zepf FD, Demisch L, et al. Influence of rapid tryptophan depletion on laboratory-provoked aggression in children with ADHD. Neuropsychobiology 2007;56:104-10.

105. Zepf FD, Stadler C, Demisch L, et al. Serotonergic functioning and trait-impulsivity in attention-deficit/hyperactivity-disordered boys (ADHD): influence of rapid tryptophan depletion. Hum Psychopharmacol 2008;23:43-51.

106. Nemzer ED, Arnold LE, Votolato NA, McConnell H. Amino acid supplementation as therapy for attention deficit disorder. J Am Acad Child Psychiatry 1986;25:509-13.

107. Poggiogalle E, Fontana M, Giusti AM, et al. Amino Acids and Hypertension in Adults. Nutrients 2019;11:1459.

108. Feltkamp H, Meurer KA, Godehardt E. Tryptophan-induced lowering of blood pressure and changes of serotonin uptake by platelets in patients with essential hypertension. Klin Wochenschr 1984;62:1115–9.

109. Cade JR, Fregly MJ, Privette M. Effect of tryptophan and 5-hydroxytryptophan on the blood pressure of patients with mild to moderate hypertension. Amino Acids 1992;2:133–42.

110. Young SN. Behavioral effects of dietary neurotransmitter precursors: basic and clinical aspects. Neurosci Biobehav Rev 1996;20:313-23 [review].

111. Riemann D, Vorderholzer U. Treatment of depression and sleep disorders. Significance of serotonin and L-tryptophan in pathophysiology and therapy. Fortschr Med 1998;116:40-2 [review].

112. Chouinard G, Jones BD, Young SN, Annable L. Potentiation of lithium by tryptophan in a patient with bipolar illness. Am J Psychiatry 1979;136:719-20.

113. Hedaya RJ. Pharmacokinetic factors in the clinical use of tryptophan. J Clin Psychopharmacol 1984;4:347-8.

114. Prange AJ, Wilson IC, Lynn CW, et al. L-tryptophan in mania: contribution to a permissive hypothesis of affective disorders. Arch Gen Psychiatry 1974;30:56-62.

115. Chambers CA, Naylor GJ. A controlled trial of L-tryptophan in mania. Br J Psychiatry 1978;132:555-9.

116. Murphy DL, Maker M, Goodwin FK, et al. L-tryptophan in affective disorders: indoleamine changes and differential clinical effects. Psychopharmacologia 1974;34:11-20.

117. van Praag HM, de Haan S. Chemoprophylaxis of depressions. An attempt to compare lithium with 5-hydroxytryptophan. Acta Psychiatr Scand Suppl 1981;290:191-201.

118. Mendlewicz J, Youdim MB. Antidepressant potentiation of 5-hydroxytryptophan by L-deprenil in affective illness. J Affect Disord 1980;2:137-46.

119. Payne IR, Walsh EM, Whittenburg EJ. Relationship of dietary tryptophan and niacin to tryptophan metabolism in schizophrenics and nonschizophrenics. Am J Clin Nutr 1974;27:565-71.

120. Gilmour DG, Manowitz P, Frosch WA, Shopsin B. Association of plasma tryptophan levels with clinical change in female schizophrenic patients. Biol Psychiatry 1973;6:119-28.

121. Morand C, Young SN, Ervin FR. Clinical response of aggressive schizophrenics to oral tryptophan. Biol Psychiatry 1983;18:575-8.

122. Levkovitz Y, Ophir-Shaham O, Bloch Y, et al. Effect of L-tryptophan on memory in patients with schizophrenia. J Nerv Ment Dis 2003;191:568-73.

123. Brewerton TD, Reus VI. Lithium carbonate and L-tryptophan in the treatment of bipolar and schizoaffective disorders. Am J Psychiatry 1983;140:757-60.

124. Gillin JC, Kaplan JA, Wyatt RJ. Clinical effects of tryptophan in chronic schizophrenic patients. Biol Psychiatry 1976;11:635-9.

125. Rosse RB, Schwartz BL, Zlotolow S, et al. Effect of a low-tryptophan diet as an adjuvant to conventional neuroleptic therapy in schizophrenia. Clin Neuropharmacol 1992;15:129-41.

126. Iversen SD. 5-HT and anxiety. Neuropharmacology 1984;23:1553-60 [review].

127. Schruers K, Klaassen T, Pols H, et al. Effects of tryptophan depletion on carbon dioxide provoked panic in panic disorder patients. Psychiatry Res 2000;93:179-87.

128. Argyropoulos SV, Hood SD, Adrover M, et al. Tryptophan depletion reverses the therapeutic effect of selective serotonin reuptake inhibitors in social anxiety disorder. Biol Psychiatry 2004;56:503-9.

129. Hudson C, Hudson S, MacKenzie J. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Can J Physiol Pharmacol 2007;85:928-32.

130. Zang DX. A self body double blind clinical study of L-tryptophan and placebo in treated neurosis. Zhonghua Shen Jing Jing Shen Ke Za Zhi 1991;24:77-80,123-4 [in Chinese].

131. Hartmann E, Spinweber CL. Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake. J Nerv Ment Dis 1979;167:497-9.

132. Snyder S, Hams G. Serotoninergic agents in the treatment of isolated sleep paralysis. Am J Psychiatry 1982;139:1202-3.

133. Fernstrom JD, Faller DV. Neutral amino acids in the brain: Changes in response to food ingestion. J Neurochem 1978;30:1531-8.

134. Hartmann E, Spinweber CL. Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake. J Nerv Ment Dis 1979;167:497-9.

135. Snyder S, Hams G. Serotoninergic agents in the treatment of isolated sleep paralysis. Am J Psychiatry 1982;139:1202-3.

136. Fernstrom JD, Faller DV. Neutral amino acids in the brain: Changes in response to food ingestion. J Neurochem 1978;30:1531-8.

137. Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002; (1):CD003198.

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140. Morgan B, Morgan R. Brainfood: nutrition and your brain. Tucson, Arizona: The Body Press, 1987.

141. Blackburn WD. Eosinophilic myalgia syndrome. Semin Arth Rheum 1997;26:788-93.

142. Slutsker L, Hoesly FC, Miller L, et al. Eosinophilia-myalgia syndrome associated with exposure to tryptophan from a single manufacturer. JAMA 1990;264:213-7.

143. Kilbourne EM, Philen RM, Kamb ML, Falk H. Tryptophan produced by Showa Denko and epidemic eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:81-8.

144. Schlessel K, Greenwald R, Hirschfield L. Scleroderma-like fasciitis without eosinophilia after L-tryptophan ingestion. J Rheumatol 1991;18:779-82.

145. Feroze K, Venkitakrishnan S, Manoj J. L-tryptophan and scleroderma: significance of nutritional supplements containing L-tryptophan. J Postgrad Med 2008;54:235-6.

146. Mensing H. L-tryptophan ingestion does not induce progressive systemic sclerosis (scleroderma). Dermatology 1992;185:173-4.

147. Freundlich B, Werth VP, Rook AH, et al. L-tryptophan ingestion associated with eosinophilic fasciitis but not progressive systemic sclerosis. Ann Intern Med 1990;112:758-62.

148. Devoe LD, Castillo RA, Searle NS, Searle JR. Maternal dietary substrates and human fetal biophysical activity. I. The effects of tryptophan and glucose on fetal breathing movements. Am J Obstet Gynecol 1986;155:135-9.

149. Meier AH, Wilson JM. Tryptophan feeding adversely influences pregnancy. Life Sci 1983;32:1193-6.

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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2025.