How the enterohepatic loop conserves bile acids
Bile acids are made in the liver from cholesterol, stored in the gallbladder, and released into the small intestine after a meal to emulsify dietary fat into droplets that lipase can digest. Rather than being lost, roughly 95 percent are actively reabsorbed in the terminal ileum and carried back to the liver through the portal vein, then re-secreted. This recycling can run several times per meal, so the body maintains a large functional pool from modest daily synthesis.
Bile acids as signaling molecules, not just detergents
Beyond fat digestion, bile acids act as signaling molecules. They bind receptors such as FXR and TGR5 that influence cholesterol and glucose handling and the secretion of gut hormones, and they shape the microbial community in the colon (while microbes in turn modify the bile acids). This crosstalk is an active research area, so many proposed health links remain preliminary.
Disruption of the loop, for example after ileal disease or resection, can cause bile-acid diarrhea. This is general educational information, not medical advice; relevant symptoms should be evaluated by a qualified clinician.