二十二碳六烯酸（DHA）循环通过长爪沙鼠体内从 ALA 更高合成来维持血液和组织浓度所需的 DHA 补充量减半。

DHA Cycling Halves the DHA Supplementation Needed to Maintain Blood and Tissue Concentrations via Higher Synthesis from ALA in Long-Evans Rats.

机构信息

Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.

Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada.

出版信息

J Nutr. 2019 Apr 1;149(4):586-595. doi: 10.1093/jn/nxy282.

DOI:10.1093/jn/nxy282

PMID:30715388

Abstract

BACKGROUND

Eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) recommendations are frequently stated at 500 mg/d; however, adherence to these recommendations would result in a large global commercial EPA/DHA production deficit. Previously, our laboratory demonstrated that acute DHA intake in rats can increase the capacity for synthesis-secretion of n-3 (ω-3) polyunsaturated fatty acids (PUFAs).

OBJECTIVE

We aimed to investigate the utility of a dietary DHA cycling strategy that employs 2 wk of repeated DHA feeding for a total of 3 cycles over 12 wk.

METHODS

Male Long-Evans rats were fed a 10% fat diet by weight comprised of either 1) a 2-wk, 2% α-linolenic acid (ALA, DHA-ALA group 18:3n-3) diet followed by a 2-wk, 2% DHA + 2% ALA diet over 3 consecutive 4-wk periods ("DHA cycling," DHA-ALA group); 2) a 2% DHA + 2% ALA diet (DHA group) for 12 wk; or 3) a 2% ALA-only diet (ALA group) for 12 wk. At 15 wk old, blood and tissue fatty acid concentrations and liver mRNA expression and 13C-DHA natural abundances were determined.

RESULTS

DHA concentrations in plasma, erythrocytes, and whole blood between the DHA-ALA group and the DHA groups were not different (P ≥ 0.05), but were 72-110% higher (P < 0.05) than in the ALA group. Similarly, DHA concentrations in liver, heart, adipose, and brain were not different (P ≥ 0.05) between the DHA-fed groups, but were at least 62%, 72%, 320%, and 68% higher (P < 0.05) than in the ALA group in liver, heart, adipose, and skeletal muscle, respectively. Compound-specific isotope analysis indicated that 310% more liver DHA in the DHA-ALA group compared with the DHA group is derived from dietary ALA, and this was accompanied by a 123% and 93% higher expression of elongation of very long-chain (Elovl)2 and Elovl5, respectively, in the DHA-ALA group compared with the ALA group.

CONCLUSIONS

DHA cycling requires half the dietary DHA while achieving equal blood and tissue DHA concentrations in rats. Implementation of such dietary strategies in humans could reduce the gap between global dietary n-3 PUFA recommendations and commercial production.

摘要

背景

二十碳五烯酸（EPA）加二十二碳六烯酸（DHA）的推荐摄入量通常为 500mg/d；然而，遵循这些建议将导致全球范围内 EPA/DHA 生产的巨大商业缺口。此前，我们实验室证明，大鼠急性 DHA 摄入可增加 n-3（ω-3）多不饱和脂肪酸（PUFA）的合成-分泌能力。

目的

我们旨在研究一种膳食 DHA 循环策略的实用性，该策略采用重复 DHA 喂养 2 周，共进行 3 个周期，持续 12 周。

方法

雄性长耳大白鼠以 10%脂肪饮食喂养，重量比为 1）2 周 2%α-亚麻酸（ALA，DHA-ALA 组 18:3n-3）饮食，随后连续 3 个 4 周周期的 2 周 2%DHA+2%ALA 饮食（DHA 循环，DHA-ALA 组）；2）12 周 2%DHA+2%ALA 饮食（DHA 组）；或 3）12 周 2%ALA 饮食（ALA 组）。在 15 周龄时，测定血液和组织脂肪酸浓度以及肝脏 mRNA 表达和 13C-DHA 天然丰度。

结果

DHA-ALA 组和 DHA 组之间血浆、红细胞和全血中的 DHA 浓度没有差异（P≥0.05），但分别比 ALA 组高 72-110%（P<0.05）。同样，DHA 组之间肝、心、脂肪和脑的浓度没有差异（P≥0.05），但分别比肝、心、脂肪和骨骼肌中的 ALA 组高至少 62%、72%、320%和 68%（P<0.05）。特异性同位素分析表明，DHA-ALA 组肝脏中的 DHA 有 310%来自膳食 ALA，与 ALA 组相比，该组中长链延伸酶 Elovl2 和 Elovl5 的表达分别增加了 123%和 93%。