EC Nutrition

Tryptophan, a large neutral amino acid (LNAA), was discovered in 1900s when it was isolated from a milk protein called casein [1]. Soon thereafter its molecular structure determined and the existence of two isomeric forms of tryptophan vis; L-tryptophan and D-tryptophan was reported. It was found to be an essential amino acid which like other amino acids served as building block of many important peptides and proteins. Apart from its essential role in the synthesis of proteins, it was found to be the precursor of many important biologically active compounds such as serotonin, melatonin and kynurenine which played critical role in maintaining metabolic and physiologic homeostasis [2,3].

 Keywords: Tryptophan; Depression; Diabetes; Obesity; Metabolism

1. Hopkins FG and Cole SW. “A contribution to the chemistry of proteids: Part II. The constitution of tryptophane and the action of bacteria upon it”. Journal of Physiology 4-5 (1903): 451-466.
2. Correia AS and Vale N. “Tryptophan metabolism in depression: a narrative review with a focus on serotonin and kynurenine pathways”. International Journal of Molecular Sciences 15 (2022): 8493.
3. Haleem DJ. “Improving therapeutics in anorexia nervosa with tryptophan”. Life Sciences 178 (2017): 87-93.
4. Haleem DJ. “Nutritional importance of tryptophan for improving treatment in depression and diabetes”. Nutrition Reviews1 (2023): 133-149.
5. Xue C., et al. “Tryptophan metabolism in health and disease”. Cell Metabolism 8 (2023): 1304-1326.
6. Iqbal J and Hussain MM. “Intestinal lipid absorption”. American Journal of Physiology-Endocrinology and Metabolism 6 (2009): E1183-E1194.
7. Haub S., et al. “Serotonin receptor type 3 antagonists improve obesity-associated fatty liver disease in mice”. Journal of Pharmacology and Experimental Therapeutics 3 (2011): 790-798.
8. Stunes AK., et al. “Adipocytes express a functional system for serotonin synthesis, reuptake and receptor activation”. Diabetes, Obesity and Metabolism 6 (2011): 551-558.
9. Hansson B., et al. “Serotonin (5-HT) and 5-HT2A receptor agonists suppress lipolysis in primary rat adipose cells”. Biochemical and Biophysical Research Communications 2 (2016): 357-363.
10. Widner B., et al. “Simultaneous measurement of serum tryptophan and kynurenine by HPLC”. Clinical Chemistry 12 (1997): 2424-2426.
11. Hagen IV., et al. “Serum concentrations of amino acids and tryptophan metabolites are affected by consumption of a light breakfast: a clinical intervention study in adults with overweight or obesity”. BMC Nutrition 1 (2023): 10.