title: Effects of the ratio of polyunsaturated and monounsaturated fatty acid to saturated fatty acid on rat plasma and liver lipid concentrations.
abstract: The effects of dietary monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid + MUFA/saturated fatty acid (PUFA + MUFA/SFA) ratio on plasma and liver lipid concentrations were studied. In experiment I, when rats were fed with 40% fat (energy%, PUFA/SFA ratio 1.0) and 1% (w/w) cholesterol (C) diets for 21 d, a large amount of MUFA (28.1 energy%, PUFA + MUFA/SFA = 5.7) in the diet was found to increase the plasma total C, triacylglycerol (TAG), and phospholipid (PL) as compared with the low-MUFA diet (7.0 energy%, PUFA + MUFA/SFA = 1.4). The plasma very low density lipoprotein (VLDL)-C, VLDL-TAG, VLDL-PL, and low density lipoprotein (LDL)-C increased significantly in the high-MUFA diet group, but high density lipoprotein (HDL)-C did not change significantly. The high-MUFA diet resulted in greater accumulation of liver C but lesser accumulation of TAG. In experiment II, when dietary SFA was fixed at a certain level (13.2 energy%; PUFA + MUFA/SFA = 2.0), rats given a larger amount of MUFA (23.1 energy%; PUFA/MUFA = 0.2; MUFA/SFA = 1.8) showed higher plasma and liver C levels than did the low-MUFA diet (7.7 energy%; PUFA/MUFA = 2.5; MUFA/SFA = 0.6). When PUFA was fixed at a certain level (24.4 energy%), there was not a significant difference in the plasma C level between the high- and low-MUFA dietary groups (PUFA + MUFA/SFA = 4.8 and 8.4), but the higher PUFA + MUFA/SFA diet, which was high in MUFA/SFA ratio, significantly decreased the plasma HDL-C and TAG levels. However, when MUFA content was fixed at a certain level (16.4 energy%), no significant difference was observed between the two groups with different PUFA/SFA ratios of 0.2 and 4.1, but liver C level was raised in the higher PUFA/SFA diet. It appears that the PUFA/SFA ratio alone is unsuitable to predict the change of plasma C level, because a large amount of dietary MUFA may lead to an increase of plasma and liver lipids in rats. It seems that the prerequisites for keeping low plasma and liver C are (i) low MUFA/SFA ratio, (ii) high PUFA/MUFA ratio, and (iii) PUFA + MUFA/SFA ratio not to exceed 2.
authors.affiliation: Department of Biochemistry, China Medical College, Taichung, Taiwan, Republic of China. nwchang@mail.cmc.edu.tw
authors.forename: N W
authors.initials: NW
authors.lastname: Chang
authors.forename: P C
authors.initials: PC
authors.lastname: Huang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002784:Cholesterol / Q000097:blood; D004041:Dietary Fats; D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids / Q000032:analysis; D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated; D005243:Feces / Q000737:chemistry; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008099:Liver / Q000378:metabolism*; D008297:Male; D010743:Phospholipids / Q000097:blood / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014280:Triglycerides / Q000097:blood / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated; D008055:Lipids; D008074:Lipoproteins; D010743:Phospholipids; D014280:Triglycerides; D002784:Cholesterol