ABSTRACT Obesity increases protein metabolism with a potential effect on nitrogen isotope fractionation. The aim of this study was to test the influence of obesity on human milk extracted protein 15N natural isotope abundance (NIA) at one month post-partum and to compare human milk extracted protein 15N NIA and bulk infant hair 15N NIA. This cross-sectional observational study involved 16 obese mothers (body mass index (BMI) ≥ 30 kg m−2 before pregnancy) matched with 16 normal-weight mothers (18.5 kg m−2 ≤ BMI < 25 kg m−2) for age and pregnancy characteristics. Human milk extracted protein and bulk infant hair 15N NIA were determined by isotope ratio monitoring by mass spectrometry interfaced to an elemental analyser (IRM-EA/MS). No significant difference was found in human milk protein 15N NIA values between obese and normal-weight mothers (8.93 ± 0.48 ‰ vs. 8.95 ± 0.27 ‰). However, human milk protein 15N NIA was significantly lower than bulk infant hair 15N NIA: 8.94 ± 0.38 ‰ vs. 9.66 ± 0.69 ‰, respectively. On the basis of these results, it is concluded that human milk protein 15N NIA measured at one month post-partum is not influenced by maternal obesity. These findings suggest that 15N NIA may be exploited to study metabolism without considering maternal obesity as a confounder.

中文翻译：

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孕产妇肥胖不影响人乳蛋白 15N 天然同位素丰度

摘要 肥胖会增加蛋白质代谢，对氮同位素分馏有潜在影响。本研究的目的是测试肥胖对产后 1 个月人乳提取蛋白 15N 天然同位素丰度 (NIA) 的影响，并比较人乳提取蛋白 15N NIA 和大量婴儿毛发 15N NIA。这项横断面观察性研究涉及 16 名肥胖母亲（怀孕前体重指数 (BMI) ≥ 30 kg m-2）与 16 名正常体重母亲（18.5 kg m-2 ≤ BMI < 25 kg m-2）的年龄匹配和妊娠特征。母乳提取的蛋白质和大量婴儿毛发 15N NIA 通过同位素比监测通过质谱仪与元素分析仪 (IRM-EA/MS) 连接来确定。肥胖母亲和正常体重母亲之间的人乳蛋白 15N NIA 值没有发现显着差异 (8. 93 ± 0.48 ‰ 与 8.95 ± 0.27 ‰）。然而，人乳蛋白 15N NIA 显着低于散装婴儿毛发 15N NIA：分别为 8.94 ± 0.38 ‰ 和 9.66 ± 0.69 ‰。基于这些结果，可以得出结论，产后 1 个月测量的人乳蛋白 15N NIA 不受母亲肥胖的影响。这些发现表明 15N NIA 可用于研究新陈代谢，而无需将母亲肥胖视为混杂因素。