STEARIC-ACID, TRANS-FATTY-ACIDS, AND DAIRY FAT - EFFECTS ON SERUM ANDLIPOPROTEIN LIPIDS, APOLIPOPROTEINS, LIPOPROTEIN(A), AND LIPID TRANSFER PROTEINS IN HEALTHY-SUBJECTS

To compare the effects on serum lipoproteins of stearic acid, trans fa tty acids, and dairy fat, 80 healthy subjects consumed a dairy fat-bas ed (baseline) diet for 5 wk, then an experimental diet high in either trans fatty acids (8.7% of energy; n = 40) or stearic acid (9.3% of en ergy; n = 40) for another 5 wk. All diets provided 32.2-33.9% of energ y as fat, 14.6-15.8% as saturated plus trans fatty acids, 11.4-12.5% a s cis-monounsaturated fatty acids, 2.9-3.5% as polyunsaturated fatty a cids, and 200-221 mg cholesterol/10 MJ. Compared with the dairy fat di et, stearic acid and trans fatty acids decreased serum total cholester ol concentrations similarly (by 13% and 12%, respectively, P < 0.001) but the trans fatty acid diet decreased HDL cholesterol (17%) and apol ipoprotein (ape) A-I (15%) significantly more than did the stearic aci d diet (11% and 12%, respectively). Stearic acid but not trans fatty a cids reduced concentrations of LDL cholesterol and apo B significantly (P < 0.001). The trans fatty acid diet increased the ratio of LDL to HDL cholesterol (19%) and of apo B to apo A-I (16%) more than did the dairy fat diet (P < 0.001) but the stearic acid diet had no effect. Li poprotein(a) concentrations increased with both experimental diets, si gnificantly more with trans fatty acids (30%) than with stearic acid ( 10%). In conclusion, high amounts of trans fatty acids had more advers e effects on lipoproteins than did equal amounts of stearic acid and d airy fat. Stearic acid reduced LDL cholesterol, did not affect the rat io of LDL to HDL cholesterol, and increased lipoprotein(a), although t o a lesser extent than did trans fatty acids. Dietary fats low in both saturated fatty acids and trans fatty acids should be favored.