Bile Acids as Integrators of Nutrient Sensing and Postprandial Metabolism.

Bile acids (BAs) are increasingly recognized as signaling molecules, with functions that extend far beyond their classical role in lipid digestion. Acting through receptors such as the farnesoid X receptor and the Takeda G protein-coupled receptor, BAs integrate nutrient-derived signals to coordinate energy expenditure, glucose and lipid metabolism, and immune responses. In the postprandial state, circulating BAs are among the most dynamically modulated metabolites. BA profiles are shaped by diet composition, sex, age, and metabolic status, while the gut microbiota diversifies BA pool composition by generating secondary BA species with distinct receptor affinities and influencing host physiology. Dysregulation of BA kinetics or pool composition is closely linked to metabolic diseases including obesity, type 2 diabetes, and metabolic dysfunction-associated steatohepatitis. This review highlights how changes in BA levels in the postprandial period coordinate enterohepatic flux, hormonal feedback, and microbiota interactions to regulate postprandial metabolic homeostasis.