Chang N W, Huang P C
Department of Biochemistry, China Medical College, Taichung, Taiwan, Republic of China.
Lipids. 1998 May;33(5):481-7. doi: 10.1007/s11745-998-0231-9.
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.
研究了膳食单不饱和脂肪酸（MUFA）以及多不饱和脂肪酸+MUFA/饱和脂肪酸（PUFA+MUFA/SFA）比值对血浆和肝脏脂质浓度的影响。在实验I中，当给大鼠喂食含40%脂肪（能量百分比，PUFA/SFA比值为1.0）和1%（w/w）胆固醇（C）的日粮21天时，发现日粮中大量的MUFA（28.1能量%，PUFA+MUFA/SFA=5.7）与低MUFA日粮（7.0能量%，PUFA+MUFA/SFA=1.4）相比，会增加血浆总胆固醇（C）、三酰甘油（TAG）和磷脂（PL）。高MUFA日粮组的血浆极低密度脂蛋白（VLDL）-C、VLDL-TAG、VLDL-PL和低密度脂蛋白（LDL）-C显著增加，但高密度脂蛋白（HDL）-C没有显著变化。高MUFA日粮导致肝脏胆固醇积累更多，但TAG积累较少。在实验II中，当膳食饱和脂肪酸（SFA）固定在一定水平（13.2能量%；PUFA+MUFA/SFA=2.0）时，给予较多MUFA（23.1能量%；PUFA/MUFA=0.2；MUFA/SFA=1.8）的大鼠血浆和肝脏胆固醇水平高于低MUFA日粮组（7.7能量%；PUFA/MUFA=2.5；MUFA/SFA=0.6）。当多不饱和脂肪酸（PUFA）固定在一定水平（24.4能量%）时，高、低MUFA日粮组之间的血浆胆固醇水平没有显著差异（PUFA+MUFA/SFA=4.8和8.4），但MUFA/SFA比值较高的高PUFA+MUFA/SFA日粮显著降低了血浆HDL-C和TAG水平。然而，当MUFA含量固定在一定水平（16.4能量%）时，PUFA/SFA比值分别为0.2和4.1的两组之间未观察到显著差异，但较高PUFA/SFA日粮组的肝脏胆固醇水平升高。似乎仅PUFA/SFA比值不足以预测血浆胆固醇水平的变化，因为大量的膳食MUFA可能导致大鼠血浆和肝脏脂质增加。看来保持低血浆和肝脏胆固醇的前提条件是：（i）低MUFA/SFA比值；（ii）高PUFA/MUFA比值；（iii）PUFA+MUFA/SFA比值不超过2。
