INFLUENCE OF DIETARY EGG AND SOYBEAN PHOSPHOLIPIDS AND TRIACYLGLYCEROLS ON HUMAN SERUM-LIPOPROTEINS

Human serum lipid and lipoprotein concentrations and compositions were compared in ten healthy middle-aged men consuming phospholipids from egg or from soybean or triacylglycerol mixtures with fatty acid compositions similar to those of the phospholipids. All subjects followed each of the four treatments: egg phospholipids (EP), soybean phospholipids (SP), an oil of fatty acid composition similar to that of EP, and an oil similar in fatty acid composition to SP for six weeks with ''wash-out'' periods of similar duration between treatment periods. The phospholipids, 15 g/d, and the oils, 12 g/d, which contained approximately equivalent quantities of fatty acids were provided to the subjects in gelatin capsules and were taken before meals. Diet intake was monitored by three-day food records. Serum lipoproteins (L(p)) were separated by ultra-centrifugation into very low density lipoproteins, low density lipoproteins (LDL), high density lipoproteins (HDL)2 and HDL3. L(p) fractions and whole serum were analyzed for triacylglycerols, cholesterol (CH), phospholipids (PL), and protein. HDL cholesterol was determined in whole serum. Cholesteryl esters were determined in some L(p) fractions. Lipid compositions of L(p) were expressed in mmol/g protein. Apoprotein B was measured in whole serum and in LDL; apoprotein A-I in whole serum and in HDL3. In whole serum, CH and PL were significantly lower after the SP compared to EP treatment periods. CH, but not PL, was lower after SPTG compared to EP. CH in HDL2 was significantly higher after SP compared to SPTG. Also, PL in HDL2 were significantly higher after SP compared to all other treatments and to baseline. Although human serum lipid responses to dietary phospholipids were generally the same as responses to ingested oils of comparable fatty acid composition, the data suggest the possibility that SP selectively increase HDL2 cholesterol and phospholipids.