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):525S-530S. doi: 10.1093/jn/127.3.525S.
Current dietary recommendations advocate reductions in saturated fatty acids (SFA) and cholesterol (C) as a primary intervention for achieving a more desirable plasma lipid profile. To ascertain whether it is more efficacious to decrease dietary lauric and myristic acids (12:0 + 14:0) or dietary palmitic acid (16:0) in conjunction with a reduction in dietary C, 11 rhesus monkeys (8 males, 3 females) were initially fed a control diet rich in SFA + C for 14 wk [dietary fat approximately 38% of energy (%en), SFA 16%en and C at 180 mg/1000 kcal]. Plasma lipids were measured between the 9th and 13th wk, and LDL metabolism was assessed after 13 wk. Monkeys were then split into two groups and fed one of two American Heart Association (AHA) Step 1 diets (approximately 30%en fat, 10%en SFA, 75 mg cholesterol/1000 kcal) for an additional 14 wk, and plasma lipids and LDL metabolism were re-evaluated. Group 1 received a 16:0-rich diet in which most 12:0 + 14:0 were deleted (approximately 8.6%en from 16:0 and approximately 0.3%en from 12:0 + 14:0), whereas Group 2 received a diet rich in 12:0 + 14:0 from which 16:0 was selectively removed (2.6%en from 16:0 and approximately 6.3%en 12:0 + 14:0). In all three diets, oleic and linoleic acid were held relatively constant so that only SFA, the level of total fat and cholesterol were manipulated. Only the Step 1 diet that selectively removed 12:0 + 14:0 (the 16:0-rich diet) significantly reduced all lipid fractions, including total cholesterol (TC), HDL-C, LDL-C, apolipoprotein B (apoB) and the LDL pool size. Plasma triglyceride (TG) and the ratio of TC/HDL-C were not altered by either Step 1 diet. The smaller LDL pool size following the 16:0-rich diet in Group 1 was attributable to a significantly higher fractional catabolic rate (FCR) of LDL because the transport rate of LDL apoB was unaffected. Although the FCR was increased with the 12:0 + 14:0-rich diet, the LDL apoB pool was not affected because the transport rate of LDL tended to increase as well. The data suggest that a Step 1 diet that reduces total fat by decreasing 12:0 + 14:0 in conjunction with dietary C, improves plasma lipids more favorably than a similar diet that selectively removes 16:0 and C. Previous data would imply that the benefit resulted from removal of 12:0 + 14:0 per se, but the possibility is not eliminated that removal of C (independent of 12:0 + 14:0) muted the potential interaction between C and palmitic acid that tends to raise TC.
当前的饮食建议主张减少饱和脂肪酸（SFA）和胆固醇（C）的摄入，作为改善血浆脂质谱的主要干预措施。为了确定在减少膳食C的同时，减少膳食月桂酸和肉豆蔻酸（12:0 + 14:0）或膳食棕榈酸（16:0）哪种更有效，11只恒河猴（8只雄性，3只雌性）最初喂食富含SFA + C的对照饮食14周[膳食脂肪约占能量的38%（%en），SFA为16%en，C为180 mg/1000 kcal]。在第9周和第13周之间测量血浆脂质，并在13周后评估低密度脂蛋白（LDL）代谢。然后将猴子分成两组，再喂食两种美国心脏协会（AHA）第一步饮食中的一种（约30%en脂肪，10%en SFA，75 mg胆固醇/1000 kcal）14周，并重新评估血浆脂质和LDL代谢。第1组接受富含16:0的饮食（其中大部分12:0 + 14:0被去除，约8.6%en来自16:0，约0.3%en来自12:0 + 14:0），而第2组接受富含12:0 + 14:0的饮食，其中16:0被选择性去除（2.6%en来自16:0，约6.3%en来自12:0 + 14:0）。在所有三种饮食中，油酸和亚油酸保持相对恒定，因此仅对SFA、总脂肪水平和胆固醇进行了调整。只有选择性去除12:0 + 14:0的第一步饮食（富含16:0的饮食）显著降低了所有脂质组分，包括总胆固醇（TC）、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）、载脂蛋白B（apoB）和LDL池大小。两种第一步饮食均未改变血浆甘油三酯（TG）和TC/HDL-C比值。第1组富含16:0的饮食后较小的LDL池大小归因于LDL的分解代谢率（FCR）显著升高，因为LDL apoB的转运速率未受影响。尽管富含12:0 + 14:0的饮食使FCR增加，但LDL apoB池未受影响，因为LDL的转运速率也趋于增加。数据表明，通过减少12:0 + 14:0并结合膳食C来降低总脂肪的第一步饮食，比选择性去除16:0和C的类似饮食更有利于改善血浆脂质。先前的数据表明，益处源于12:0 + 14:0本身的去除，但不能排除去除C（独立于12:0 + 14:0）减弱了C与倾向于升高TC的棕榈酸之间潜在相互作用的可能性。
