Khosla P, Hajri T, Pronczuk A, Hayes K C
Foster Biomedical Research Laboratory, Brandeis University, Waltham, MA 02254, USA.
J Nutr. 1997 Mar;127(3):531S-536S. doi: 10.1093/jn/127.3.531S.
The question whether dietary trans fatty acids affect lipoprotein metabolism similarly to specific saturated fatty acids was investigated in 11 normolipemic cebus monkeys by exchanging 5% dietary energy (%en) between elaidic (t-C18:1 delta9) and palmitic acid (16:0) in two test diets (30%en fat + 100 mg cholesterol/1000 kcal diet) conforming to the American Heart Association (AHA) Step 1 guidelines. These were compared with a normal control diet rich in saturated fat and cholesterol (38%en fat + 180 mg cholesterol/1000 kcal diet). The control diet was fed initially for 14 wk, followed by each of the the two test diets in a crossover design. Plasma lipid concentrations were determined four times between the 6th and 14th wk. Turnover studies (using 125I-HDL and 131I-LDL) were conducted after 9 wk in each dietary period. Relative to the control diet, both test diets significantly reduced plasma total cholesterol (TC), HDL cholesterol (HDL-C) and VLDL plus LDL cholesterol (LDL-C) concentrations; triglyceride (TG) concentrations tended to be lower. However, the trans diet resulted in a significantly greater reduction in HDL-C than the palmitate diet (124 +/- 17, 117 +/- 18 and 106 +/- 13 mg/dL for the control, palmitate and trans diets, respectively). The palmitate diet significantly decreased the TC/HDL-C ratio by 11% when compared with the control diet (1.68 +/- 0.17 vs. 1.89 +/- 0.30), whereas the trans diet had no effect (1.81 +/- 0.20 vs. 1.89 +/- 0.30). Kinetic studies revealed that, relative to the control diet, both test diets significantly lowered the LDL apolipoprotein B (apoB) pool size, principally reflecting an increase in the LDL apoB fractional catabolic rate (FCR) related to the reduced cholesterol intake. Between the two test diets, no significant differences in LDL kinetic parameters were observed. Both test diets significantly decreased HDL apoA1 concentrations in comparison with the control diet, which was partly explained by an increase in the fractional catabolic rate of HDL. Of the two test diets, the trans diet was associated with a 9.5% greater HDL FCR than the palmitate diet (P < 0.08) and a significant increase in plasma cholesteryl ester transfer protein (CETP) activity (% transfer 114 +/- 7 vs. 91 +/- 7; P < 0.03). Thus, palmitic acid- and elaidic acid-rich diets produced identical effects on LDL metabolism in normocholesterolemic cebus monkeys fed diets with low levels of cholesterol, whereas elaidic acid depressed HDL-C, attributable to both increased CETP activity and HDL clearance.
通过在两种符合美国心脏协会（AHA）第一步指南的试验饮食（30%能量来自脂肪 + 100毫克胆固醇/1000千卡饮食）中，将5%的膳食能量（%en）在反式油酸（t-C18:1 delta9）和棕榈酸（16:0）之间进行交换，对11只血脂正常的卷尾猴进行研究，以探讨膳食反式脂肪酸对脂蛋白代谢的影响是否与特定饱和脂肪酸类似。将这些与富含饱和脂肪和胆固醇的正常对照饮食（38%能量来自脂肪 + 180毫克胆固醇/1000千卡饮食）进行比较。对照饮食最初喂养14周，然后采用交叉设计依次给予两种试验饮食。在第6周和第14周之间测定了4次血浆脂质浓度。在每个饮食期9周后进行周转研究（使用125I-HDL和131I-LDL）。相对于对照饮食，两种试验饮食均显著降低了血浆总胆固醇（TC）、高密度脂蛋白胆固醇（HDL-C）以及极低密度脂蛋白加低密度脂蛋白胆固醇（LDL-C）浓度；甘油三酯（TG）浓度有降低趋势。然而，反式饮食导致HDL-C的降低幅度显著大于棕榈酸饮食（对照、棕榈酸和反式饮食的HDL-C分别为124±17、117±18和106±13毫克/分升）。与对照饮食相比，棕榈酸饮食使TC/HDL-C比值显著降低了11%（1.68±0.17对1.89±0.30），而反式饮食则无影响（1.81±0.20对1.89±0.30）。动力学研究表明，相对于对照饮食，两种试验饮食均显著降低了低密度脂蛋白载脂蛋白B（apoB）池大小，主要反映了与胆固醇摄入量减少相关的低密度脂蛋白apoB分数分解代谢率（FCR）增加。在两种试验饮食之间，未观察到低密度脂蛋白动力学参数的显著差异。与对照饮食相比，两种试验饮食均显著降低了高密度脂蛋白载脂蛋白A1浓度，部分原因是高密度脂蛋白分数分解代谢率增加。在两种试验饮食中，反式饮食的高密度脂蛋白FCR比棕榈酸饮食高9.5%（P < 0.08），并且血浆胆固醇酯转移蛋白（CETP）活性显著增加（%转移114±7对91±7；P < 0.03）。因此，在喂食低胆固醇饮食的血脂正常的卷尾猴中，富含棕榈酸和反式油酸的饮食对低密度脂蛋白代谢产生相同影响，而反式油酸降低HDL-C，这归因于CETP活性增加和HDL清除率提高。
