N-lactoyl-phenylalanine

N-lactoyl-phenylalanine (Lac-Phe) is an exercise-inducible circulating metabolite produced in gut epithelial cells through the conjugation of lactate and phenylalanine, recently identified as a potent suppressor of feeding behaviour and adiposity in mammals. Li et al. (2022) in Nature demonstrated that Lac-Phe is one of the most strongly exercise-responsive metabolites in humans, with plasma levels rising in proportion to exercise intensity. As a salivary marker, it reflects the acute metabolic response to high-intensity muscular effort and energy expenditure.