Hodson Leanne, McQuaid Siobhán E, Karpe Fredrik, Frayn Keith N, Fielding Barbara A
Oxford Centre for Diabetes, Endocrinology, and Metabolism, Churchill Hospital, Oxford OX3 7LJ, UK.
Am J Physiol Endocrinol Metab. 2009 Jan;296(1):E64-71. doi: 10.1152/ajpendo.90730.2008. Epub 2008 Oct 21.
There has been much interest in the health effects of dietary fat, but few studies have comprehensively compared the acute metabolic fate of specific fatty acids in vivo. We hypothesized that different classes of fatty acids would be variably partitioned in metabolic pathways and that this would become evident over 24 h. We traced the fate of fatty acids using equal amounts of [U-(13)C]linoleate, [U-(13)C]oleate, and [U-(13)C]palmitate given in a test breakfast meal in 12 healthy subjects. There was a tendency for differences in the concentrations of the tracers in plasma chylomicron-triacylglycerol (TG) (oleate > palmitate > linoleate). This pattern remained in plasma nonesterified fatty acid (NEFA) and very low-density lipoprotein (VLDL)-TG (P <or= 0.01 and P <or= 0.02 for [U-(13)C]oleate vs. both [U-(13)C]palmitate and [U-(13)C]linoleate for NEFA and VLDL-TG, respectively). There was significantly more [U-(13)C]linoleate than the other two tracers in plasma cholesteryl ester and phospholipid (PL). Using the values for isotopic enrichment in the different lipid fractions compared with the test meal, we calculated the contribution of meal fatty acids to the respective fractions. At 24 h, 10% of plasma PL-linoleate originated from the breakfast test meal. This was significantly greater than for oleate and palmitate (both 3 +/- 0.3%; P < 0.05). This pattern was also true for erythrocyte PL fatty acids. The marked rapid incorporation of linoleate from a single meal into blood PL fractions may have functional consequences such as maintenance of membrane fluidity and may explain why linoleate is a useful biomarker of dietary intake.
人们对膳食脂肪对健康的影响十分关注，但很少有研究全面比较特定脂肪酸在体内的急性代谢去向。我们推测，不同种类的脂肪酸在代谢途径中的分配存在差异，且这种差异在24小时内会变得明显。我们在12名健康受试者的一顿测试早餐中给予等量的[U-(13)C]亚油酸、[U-(13)C]油酸和[U-(13)C]棕榈酸，追踪脂肪酸的去向。血浆乳糜微粒三酰甘油（TG）中示踪剂浓度存在差异趋势（油酸>棕榈酸>亚油酸）。这种模式在血浆非酯化脂肪酸（NEFA）和极低密度脂蛋白（VLDL）-TG中也存在（[U-(13)C]油酸与[U-(13)C]棕榈酸和[U-(13)C]亚油酸相比，NEFA和VLDL-TG的P值分别≤0.01和≤0.02）。血浆胆固醇酯和磷脂（PL）中[U-(13)C]亚油酸明显多于其他两种示踪剂。利用与测试餐相比不同脂质组分中同位素富集的值，我们计算了餐中脂肪酸对各组分的贡献。在24小时时，血浆PL-亚油酸的10%来自早餐测试餐。这显著高于油酸和棕榈酸（均为3±0.3%；P<0.05）。红细胞PL脂肪酸也呈现这种模式。单次餐中亚油酸迅速大量掺入血液PL组分可能具有维持膜流动性等功能后果，这或许可以解释为什么亚油酸是膳食摄入的有用生物标志物。
