The absorption of oleic acid from emulsion and micellar solution

Abstract

1. 1. The absorption of oleic acid by rat jejunum was measured in vivo by measuring uptake, incorporation into triglyceride and transport out of the intestine by tied loops of jejunum and in vitro by measuring its incorporation into triglyceride by jejunal slices. The oleic acid was dissolved at high concentration in 15 mM sodium taurocholate to compare absorption from solutions in which most was in emulsion (pH 5.8) with absorption from solutions in which most was in micellar solution (pH 7.2). 2. 2. No difference could be detected between the absorption from emulsions and absorption from micellar solution. Studies were made over a wide range of lipid concentration and, in vivo, over a wide period of time. Absorption was related only to total oleic acid concentration, regardless of its physical form. 3. 3. The in vitro technique was found to be a misleading indication of behaviour in vivo, for maximum esterification was achieved at concentrations below complete saturation of the micellar phase, whereas in vivo uptake and esterification were directly related to oleic acid concentration in the lumen throughout the range studied, no matter whether in emulsion or micellar solution. 4. 4. It is concluded that absorption can be as efficient from an emulsion as from a micellar solution and that oleic acid can be absorbed directly from emulsion droplets without passing through an intermediary micellar phase.