Kynurenines: Tryptophan’s metabolites in exercise, inflammation, and mental health

From stomach ache to depression Our gut hurts and we feel miserable. Such disparate phenomena are mechanistically connected, but how? Cervenka et al. review the many pathways taken by dietary tryptophan as it is metabolized into kynurenines. These metabolites distribute into homeostatic networks that integrate diverse aspects of mammalian physiology. Depending on physiological context, kynurenines influence health and disease states ranging from intestinal conditions to inflammation to cancer progression. Further, they can mediate the effects of exercise, mood, and neuronal excitability and, ultimately, communicate with the microbiota. Science , this issue p. eaaf9794