Institute of Food Science and Human Nutrition, Leibniz University Hannover, Germany.
Institute for Food Toxicology, University of Veterinary Medicine Hannover, Germany.
Food Funct. 2018 Mar 1;9(3):1587-1600. doi: 10.1039/c7fo01809f. Epub 2018 Feb 20.
The essential omega-3 fatty acid alpha-linolenic acid (ALA, 18:3n3) can be converted into EPA and DHA. The aim of the present study was to determine the effect of a high-ALA diet on EPA and DHA levels in red blood cells (RBCs) and their oxylipins in the plasma of subjects with a low EPA and DHA status. Fatty acid concentrations [μg mL] and relative amounts [% of total fatty acids] in the RBCs of 19 healthy men (mean age 26.4 ± 4.6 years) were analyzed by means of GC-FID. Free plasma oxylipin concentrations were determined by LC-MS based targeted metabolomics. Samples were collected and analyzed at baseline (week 0) and after 1 (week 1), 3 (week 3), 6 (week 6), and 12 (week 12) weeks of high dietary ALA intake (14.0 ± 0.45 g day). ALA concentrations significantly (p < 0.001) increased from 1.44 ± 0.10 (week 0) to 4.65 ± 0.22 (week 1), 5.47 ± 0.23 (week 3), 6.25 ± 0.24 (week 6), and 5.80 ± 0.28 (week 12) μg mL. EPA concentrations increased from 6.13 ± 0.51 (week 0) to 7.33 ± 0.33 (week 1), 8.38 ± 0.42 (p = 0.021, week 3), 10.9 ± 0.67 (p < 0.001, week 6), and 11.0 ± 0.64 (p < 0.001, week 12) μg mL. DHA concentrations unexpectedly decreased from 41.0 ± 1.93 (week 0) to 37.0 ± 1.32 (week 1), 36.1 ± 1.37 (week 3), 35.1 ± 1.06 (p = 0.010, week 6), and 30.4 ± 1.09 (p < 0.001, week 12) μg mL. Relative ΣEPA + DHA amounts were unchanged during the intervention (week 0: 4.63 ± 0.19, week 1: 4.67 ± 0.16, week 3: 4.61 ± 0.13, week 6: 4.73 ± 0.15, week 12: 4.52 ± 0.11). ALA- and EPA-derived hydroxy- and dihydroxy-PUFA increased similarly to their PUFA precursors, although in the case of ALA-derived oxylipins, the concentrations increased less rapidly and to a lesser extent compared to the concentrations of their precursor FA. LA-derived oxylipins remained unchanged and arachidonic acid and DHA oxylipin concentrations were not significantly changed. Our results confirm that the intake of ALA is not a sufficient source for the increase of EPA + DHA in subjects on a Western diet. Specifically, a high-ALA diet results in increased EPA and declined DHA concentrations. However, the changes effectively balance each other out so that ΣEPA + DHA in RBCs - which is an established marker for health protective effects of omega-3-PUFA - remains constant. The PUFA levels in RBCs reflect the concentration and its changes in plasma hydroxy- and dihydroxy-PUFA concentrations for ALA and EPA.
必需的欧米伽-3 脂肪酸 α-亚麻酸（ALA，18:3n3）可以转化为 EPA 和 DHA。本研究的目的是确定高 ALA 饮食对低 EPA 和 DHA 状态受试者 RBC 中 EPA 和 DHA 水平及其血浆中 oxylipin 的影响。通过 GC-FID 分析 19 名健康男性（平均年龄 26.4±4.6 岁）RBC 中的脂肪酸浓度[μg/mL]和相对含量[%总脂肪酸]。通过基于 LC-MS 的靶向代谢组学测定游离血浆 oxylipin 浓度。在高膳食 ALA 摄入（14.0±0.45g/d）1、3、6 和 12 周时采集和分析基线（第 0 周）和第 1（第 1 周）、3（第 3 周）、6（第 6 周）周时的样本。ALA 浓度显著（p<0.001）从 1.44±0.10（第 0 周）增加到 4.65±0.22（第 1 周）、5.47±0.23（第 3 周）、6.25±0.24（第 6 周）和 5.80±0.28（第 12 周）μg/mL。EPA 浓度从 6.13±0.51（第 0 周）增加到 7.33±0.33（第 1 周）、8.38±0.42（p=0.021，第 3 周）、10.9±0.67（p<0.001，第 6 周）和 11.0±0.64（p<0.001，第 12 周）μg/mL。DHA 浓度出人意料地从 41.0±1.93（第 0 周）降低到 37.0±1.32（第 1 周）、36.1±1.37（第 3 周）、35.1±1.06（p=0.010，第 6 周）和 30.4±1.09（p<0.001，第 12 周）μg/mL。干预期间相对ΣEPA+DHA 量保持不变（第 0 周：4.63±0.19，第 1 周：4.67±0.16，第 3 周：4.61±0.13，第 6 周：4.73±0.15，第 12 周：4.52±0.11）。ALA 和 EPA 衍生的羟基和二羟基-PUFA 与它们的 PUFA 前体相似地增加，尽管在 ALA 衍生的 oxylipin 情况下，浓度增加的速度较慢，程度较小。LA 衍生的 oxylipin 保持不变，花生四烯酸和 DHA oxylipin 浓度没有明显变化。我们的结果证实，ALA 的摄入不是增加西方饮食受试者 EPA+DHA 的足够来源。具体而言，高 ALA 饮食会导致 EPA 增加和 DHA 浓度降低。然而，这些变化有效地相互平衡，因此 RBC 中ΣEPA+DHA-这是 omega-3-PUFA 对健康保护作用的既定标志物-保持不变。RBC 中的 PUFA 水平反映了血浆中羟基和二羟基-PUFA 浓度以及 ALA 和 EPA 的变化。
