L-tryptophan is one of the basic building blocks for protein synthesis in the body and for the formation of serotonin, kynurenin derivatives, and nicotinamide. Inadequate intake or availability of tryptophan leads, on the one hand, to nitrogen balance disorders with a risk of muscle wasting and, on the other hand, to a decrease in serotonin and nicotinamide synthesis, leading to an increased risk of developing neuropsychiatric disorders or symptoms resembling pellagra (disease due to lack of niacin – vitamin B3).
Low tryptophan levels are also associated with increased inflammatory symptoms, increased sensitivity to pain, and decreased intestinal motility, particularly in patients with inflammatory bowel disease. Determination of tryptophan in feces is a simple way to detect tryptophan deficiency.
Tryptophan: The "missing link" between physical and psychiatric conditions
It is known that numerous physical diseases, such as viral infections, cardiovascular diseases, allergies, autoimmune diseases, chronic inflammatory bowel diseases, neurodegenerative diseases, cancers, and irritable bowel syndrome, are accompanied by psychological symptoms such as depression, anxiety disorders and irritability. These co-morbidities are of significant clinical significance, as there is a highly significant correlation, particularly between depression and the increased risk of cardiovascular events and increased mortality. A large amount of biochemical and clinical data has now shown that tryptophan deficiency represents the "missing link" between the physical and psychiatric conditions mentioned above.
Tryptophan in stool
Tryptophan deficiency can be detected in feces. Low levels of tryptophan in stool are associated with increased inflammatory symptoms, increased sensitivity to pain, and decreased intestinal motility. In addition, reduced tryptophan levels are associated with depression symptoms.
