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目的本项研究旨在探讨健康乳母膳食及乳汁中n-6和n-3多不饱和脂肪酸水平的关系。方法研究对象为108例来自长春的健康哺乳期妇女,孕期及哺乳期均未服用多不饱和脂肪酸补充剂。在产后20+3 d收集母乳样本,并进行3 d 24 h膳食回顾调查,用《中国食物成分表》计算5种多不饱和脂肪酸膳食摄入量。采用直接酯化一步法,应用气相色谱仪测定乳汁中8种多不饱和脂肪酸水平,其中n-6多不饱和脂肪酸5种,n-3多不饱和脂肪酸3种。结果 108例乳母乳汁中花生四烯酸(ARA)浓度(0.273±0.176)mg/ml,二十二碳六烯酸[DHA,(0.175±0.123)mg/ml,亚油酸[LA,18:2 n-6,(1.238±0.772)mg/ml],α-亚麻酸[ALA,18:3 n-3,(0.548±0.383)mg/ml],二十二碳四烯酸(C22:4n-6),为(0.065±0.041)mg/ml,二高γ-亚麻酸(C20:3 n-6),为(0.190±0.118)mg/ml,γ-亚麻酸[C18:3 n-6,为(0.131±0.115)mg/ml],二十碳五烯酸(EPA)为(0.031±0.033)mg/ml。膳食ALA和LA的摄入量呈显著正相关(r=0.746,P<0.01)。然而,膳食ALA的摄入量与母乳中的EPA水平呈显著负相关(r=-0.261,P<0.01)。结论长春108例哺乳期妇女乳汁中n-6多不饱和脂肪酸二十二碳四烯酸水平最低,n-3多不饱和脂肪酸EPA水平最低。ALA与LA竞争体内的同一脂肪酸去饱和酶,可能是膳食ALA与乳汁中EPA水平呈负相关的原因。
The purpose of this study was to investigate the relationship between n-6 and n-3 polyunsaturated fatty acids in healthy maternal diet and milk. Methods The subjects were healthy breast-feeding women from Changchun 108 cases, not taking polyunsaturated fatty acid supplements during pregnancy and lactation. Breast milk samples were collected 20 days and 3 days postpartum, and a 3 d 24 h dietary recall survey was conducted. The dietary intake of 5 kinds of polyunsaturated fatty acids was calculated using “China Food Composition Table”. One-step direct esterification method was used to determine the levels of 8 polyunsaturated fatty acids in milk, including 5 n-6 polyunsaturated fatty acids and 3 n-3 polyunsaturated fatty acids. Results The concentrations of arachidonic acid (ARA), docosahexaenoic acid [DHA (0.175 ± 0.123) mg / ml, linoleic acid [LA, 18: (N = 6, (1.238 ± 0.772) mg / ml], α-linolenic acid [ALA, 18: 3 n-3, -6) for (0.065 ± 0.041) mg / ml, C02: 3 n-6 (0.131 ± 0.115) mg / ml], and the eicosapentaenoic acid (EPA) was (0.031 ± 0.033) mg / ml. Dietary ALA and LA intake was significantly correlated (r = 0.746, P <0.01). However, dietary ALA intake was negatively correlated with EPA level in breast milk (r = -0.261, P <0.01). Conclusion 108 breast-feeding women in Changchun had the lowest level of n-6 polyunsaturated fatty acids and lowest n-3 polyunsaturated fatty acid levels in dairy cows. The same fatty acid desaturase that ALA competes with LA may be responsible for the negative association between dietary ALA and milk EPA levels.