Bile salts are detergent-like substances secreted from the gallbladder that aid in the digestion and absorption of lipids. A bile salt is made up of a bile acid and an associated cation, usually an amino acid. Examples include glycocholate and taurocholate.

Like a detergent, bile salts contain hydrophobic and hydrophilic components. The hydrophobic portions of the molecule associate with the fat, and the hydrophilic parts associate with water, serving to solubilize (emulsify) the otherwise insoluble fat. See Figure 18.4.