Linden , Maike, Katrin Helmbold, Janina Kempf, Shabnam Sippas, Christian Filss, Karl-Josef Langen, Albrecht Eisert, and Florian Daniel Zepf. “Dietary Tryptophan Depletion in Humans Using a Simplified Two Amino Acid Formula - a Pilot Study”. Food & Nutrition Research 600 (December 16, 2016). Accessed April 4, 2026. https://foodandnutritionresearch.net/index.php/fnr/article/view/958.