Bile is an emulsifier. Its surface active properties are important in the digestion and absorption of fats, and probably play a role in preventing cholesterol from precipitating in the bile. Like other surfactants, bile can be presumed to solubilize fat in a micellar fashion, analagous to the action of soaps or detergents. Rains, in 1953, demonstrated and emphasized the importance of micellar behavior in pure bile salt solutions.1 As Hofmann has indicated, bile salts in physiological concentrations within the body probably always complex in a micellar fashion.2
The micelle, as it exists in bile, is presumed to be an ionic aggregate of polar and nonpolar molecules. In the case of surfactant, evidence of micelle formation is obtained when increasing concentrations of the surfactant result in an increase or no change in the surface tension, rather than a decrease as might be expected. Similar discontinuity may be seen in