Update on Bile Acid Malabsorption: Finally Ready for Prime Time?

Purpose of Review: To provide an update on the prevalence, pathophysiology, disease associations, and treatment options for bile acid malabsorption (BAM). Recent Findings: •Molecular mechanisms—BAs prevent water reabsorption and increase water secretion by intracellular mediators, increasing aquaporin channels and intracellular permeability. •Inflammatory bowel disease—new molecular mechanisms of BAM are identified in patients without ileal disease, including changes in expression of ileal BA transporter and nuclear receptors involved in BA homeostasis. •Microscopic colitis—BAM is one of the mechanisms leading to microscopic colitis. •Diagnostic testing—new diagnostic tests have been launched in the USA (serum C4 and fecal 48-h BA excretion); stimulated FGF19 has higher detection of BAM compared to fasting sample alone. •Treatment—investigational FXR agonists may provide a daily, oral option for treatment of BAM instead of BA sequestrants. Summary: There is a greater appreciation of the biological role of bile acids across multiple fields of medicine, including gastrointestinal indications.