Department of Animal Sciences, The Pennsylvania State University, University Park, PA, USA.
Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA.
J Nutr. 2021 Jul 1;151(7):1834-1843. doi: 10.1093/jn/nxab094.
Methods to increase the amount of omega-3 (n-3) PUFAs in milk are desirable for neonatal health. The n-3 PUFA, α-linolenic acid (18:3n-3), can be elongated to EPA (20:5n-3) and DHA (22:6n-3). n-6 PUFAs suppress tissue n-3 PUFA incorporation, but the effect of SFAs is not clear.
In this study, we compared the effects of SFAs and n-6 PUFAs on n-3 PUFA incorporation into milk and tissues of lactating mice and tissues of their offspring.
Female CD-1 mice were bred at 8 wk of age. All experimental diets included 3% flaxseed oil and were begun on day 8 of lactation: low-fat diet (LFD); high-SFA diet (SAT), with an additional 12% saturated oil; or high-linoleic-acid diet (HLA), with 12% high-linoleic-acid oil (% kcal, carbohydrates:fat:protein: LFD, 49:24:27; both SAT and HLA, 35:46:19; n = 5/treatment). After 5 d, pup stomach milk clot FA profiles, tissue FA profiles in dams and pups, and mammary and hepatic expression of lipid metabolism genes in dams were analyzed. Data were analyzed by ANOVA with treatment diet as a fixed effect.
Dams in all groups had similar total milk fat concentrations, but both SAT and HLA decreased the concentration of n-3 PUFAs (SAT: -23%; HLA: -31%) compared with LFD, and HLA increased milk n-6 FAs by 347% compared with SAT. SAT pups had n-3 PUFA tissue concentrations similar to LFD, but HLA pups had lower n-3 PUFAs than SAT pups in multiple tissues (liver, -32%; kidney, -29%; heart, -28%; muscle, -18%). Mammary expression of lipid metabolism genes was mostly unchanged, but hepatic expression of elongases and desaturases was decreased with SAT compared with LFD [elongation of very-long-chain fatty acid (Elov)5, -42%; Elov6, -64%; fatty acid desaturase (Fads)1, -33%; Fads2, -44%].
HLA decreased n-3 PUFA concentrations across multiple pup tissues compared with SAT. This suggests that high dietary n-6 PUFAs suppress n-3 PUFA incorporation in neonates.
增加牛奶中ω-3（n-3）多不饱和脂肪酸（PUFAs）含量的方法有益于新生儿健康。n-3 PUFA，α-亚麻酸（18：3n-3）可被延长为 EPA（20：5n-3）和 DHA（22：6n-3）。n-6 PUFAs 抑制组织中 n-3 PUFAs 的掺入，但 SFAs 的影响尚不清楚。
本研究比较了 SFAs 和 n-6 PUFAs 对泌乳小鼠乳汁和组织以及其后代组织中 n-3 PUFA 掺入的影响。
8 周龄 CD-1 雌鼠繁殖。所有实验饮食均包含 3%亚麻籽油，并于哺乳期第 8 天开始：低脂饮食（LFD）；高饱和脂肪酸饮食（SAT），额外添加 12%饱和油；或高亚油酸饮食（HLA），添加 12%高亚油酸油（%kcal，碳水化合物：脂肪：蛋白质：LFD，49：24：27；SAT 和 HLA 均为 35：46：19；n=5/处理）。5 天后，分析幼鼠胃乳凝块 FA 谱、母鼠和幼鼠组织 FA 谱以及母鼠乳腺和肝脏中脂质代谢基因的表达。数据采用方差分析，处理饮食为固定效应。
所有组别的母鼠总乳脂浓度相似，但 SAT 和 HLA 均降低了 n-3 PUFAs 的浓度（SAT：-23%；HLA：-31%），与 LFD 相比，HLA 增加了 347%的乳内 n-6 FAs。SAT 幼鼠的 n-3 PUFA 组织浓度与 LFD 相似，但与 SAT 幼鼠相比，HLA 幼鼠的多个组织中 n-3 PUFAs 浓度更低（肝脏：-32%；肾脏：-29%；心脏：-28%；肌肉：-18%）。脂质代谢基因的乳腺表达基本不变，但与 LFD 相比，SAT 降低了肝脏延伸酶和去饱和酶的表达[延伸酶（Elov）5，-42%；Elov6，-64%；脂肪酸去饱和酶（Fads）1，-33%；Fads2，-44%]。
与 SAT 相比，HLA 降低了多个幼鼠组织中的 n-3 PUFA 浓度。这表明高膳食 n-6 PUFAs 抑制新生儿内 n-3 PUFA 的掺入。
