Egg phosphatidylcholine decreases the lymphatic absorption of cholesterol in rats

This study was conducted to determine the effects of phosphatidylcholine (P C) from different sources on intestinal absorption of cholesterol. Male Spr ague-Dawley rats were fed an AIN-93G diet containing soybean oil for 4 wk. Each rat with lymph cannula was infused via a duodenal catheter at 3.0 mL/h for 8 h with a lipid emulsion [in mu mol: 451.8 triolein, 27.8 kBq C-14-ch olesterol (CH), 20.7 CH, 3.6 alpha -tocopherol, and 100 PC in 24 mL PBS, pH 6.6]. The PC in the lipid emulsion was egg PC (EPC), hydrogenated egg PC ( HPC), or soy PC (SPC). The EPC in the lipid emulsion markedly lowered the l ymphatic absorption of C-14-CH (24.7 +/- 2.5% dose) compared with SPC (34.9 +/- 1.2%) and a lipid emulsion containing no PC (NPC) (30.8 +/- 2.0%). The HPC further lowered the absorption of C-14-CH to 21.1 +/- 1.4% dose. The o utputs of phospolipid were unaffected by the source of PC infused (EPC, 32. 2 +/- 1.7; HPC, 31.8 +/- 1.6; and SPC, 32.9 +/- 1.8 mu mol/8 h). Compared w ith NPC (595.0 +/- 59.5 mu mol), the total output of fatty acids over 8 h w as increased significantly by SPC (685.4 +/- 55.8 mu mol), but decreased by HPC (467.7 +/- 28.4 mu mol). The total lymphatic output of oleic acid (18: 1), the major fatty acid infused in the form of triolein, did not differ am ong the NPC (448.0 +/- 58.2 mu mol/8 h), SPC (457.9 +/- 52.3 mu mol/8 h) an d EPC (412.9 +/- 20.8 mu mol/8 h) groups, but was significantly lower in th e HPC group (262.0 +/- 24.1 mu mol/8 h). The findings provide the first evi dence that EPC markedly lowers the lymphatic absorption of cholesterol unde r in vivo conditions. The inhibitory effect of EPC appears to be due to the higher degree of saturation of its acyl groups relative to SPC, suggesting that the intestinal absorption of egg cholesterol may be reduced by the pr esence of PC in egg yolk.