BACKGROUND The maternal buffering hypothesis posits that human lactation biology can buffer milk against the mild-to-moderate malnutrition that occurred routinely in evolutionary history through the mobilization of maternal body reserves. This perspective may provide insights for understanding human milk immune content variation, such as milk sIgA, which protects infants' intestines from microbial colonization and prevents diarrheal disease. OBJECTIVE To investigate how maternal delivery of sIgA to milk may vary in a way that can buffer milk against maternal malnutrition, while taking into consideration infants' varying needs for immune protection across age or by sex. METHODOLOGY A cross-sectional study analyzed archived milk specimens from breastfeeding mothers in Ariaal communities of northern Kenya surveyed during the 2006 Horn-of-Africa drought. Multiple regression models for ln-transformed sIgA were constructed using maternal nutrition, infant age/sex and their interactions as predictors. Maternal nutrition variables included iron-deficiency anemia (IDA), vitamin A deficiency (VAD) and mid-upper arm circumference (MUAC). Infant vulnerability was considered high in young age and/or male sex. RESULTS AND IMPLICATIONS Milk sIgA did not significantly differ by maternal IDA. Milk sIgA increased with infant age and maternal MUAC (n = 202). Significant interactions were observed between infant age and maternal VAD and between infant sex and maternal MUAC, such that milk sIgA content was low for younger infants particularly among VAD mothers, while among mothers with low MUAC, sIgA was lower for male infants. Results imply that mothers' ability to deliver/buffer milk sIgA may be lowered when nutritional stress is combined with high infant vulnerability to infection. LAY SUMMARY Human milk sIgA antibody content was low for younger infants among vitamin A deficient mothers. Among mothers with small arm-circumference, milk sIgA was lower for sons. Double burden of raising young or male infants with high needs for immune protection and being malnourished, might lower maternal sIgA delivery to milk.

中文翻译：

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肯尼亚北部母乳 sIgA 抗体与母体营养和婴儿脆弱性的关系。

背景 母体缓冲假说假设人类泌乳生物学可以通过动员母体储备来缓冲牛奶以防止在进化史上经常发生的轻度至中度营养不良。这一观点可能为了解母乳免疫成分变化提供见解，例如牛奶 sIgA，它可以保护婴儿的肠道免受微生物定植并预防腹泻病。目的 研究母体向母乳中 sIgA 的传递如何以缓冲母乳以防止母体营养不良的方式发生变化，同时考虑到婴儿在不同年龄或不同性别对免疫保护的不同需求。方法学 一项横断面研究分析了 2006 年非洲之角干旱期间调查的肯尼亚北部 Ariaal 社区母乳喂养母亲的存档母乳样本。使用母体营养、婴儿年龄/性别及其相互作用作为预测因子构建了 ln 转化 sIgA 的多元回归模型。孕产妇营养变量包括缺铁性贫血（IDA）、维生素 A 缺乏（VAD）和中上臂围（MUAC）。婴儿的脆弱性在年轻和/或男性中被认为很高。结果和意义 母体 IDA 的牛奶 sIgA 没有显着差异。牛奶 sIgA 随着婴儿年龄和母体 MUAC 的增加而增加（n = 202）。在婴儿年龄与母亲 VAD 之间以及婴儿性别与母亲 MUAC 之间观察到显着的相互作用，因此，年幼婴儿的牛奶 sIgA 含量较低，特别是在 VAD 母亲中，而在 MUAC 较低的母亲中，男婴儿的 sIgA 含量较低。结果表明，当营养压力与婴儿对感染的高度易感性相结合时，母亲输送/缓冲牛奶 sIgA 的能力可能会降低。LAY Summary 缺乏维生素 A 的母亲中年幼婴儿的母乳 sIgA 抗体含量较低。在臂围较小的母亲中，儿子的牛奶 sIgA 较低。抚养具有高免疫保护需求和营养不良的年轻或男婴的双重负担可能会降低母体 sIgA 向母乳的输送。当营养压力与婴儿对感染的高度易感性相结合时，输送/缓冲牛奶 sIgA 的能力可能会降低。LAY Summary 缺乏维生素 A 的母亲中年幼婴儿的母乳 sIgA 抗体含量较低。在臂围较小的母亲中，儿子的牛奶 sIgA 较低。抚养具有高免疫保护需求和营养不良的年轻或男婴的双重负担可能会降低母体 sIgA 向母乳的输送。当营养压力与婴儿对感染的高度易感性相结合时，输送/缓冲牛奶 sIgA 的能力可能会降低。LAY Summary 缺乏维生素 A 的母亲中年幼婴儿的母乳 sIgA 抗体含量较低。在臂围较小的母亲中，儿子的牛奶 sIgA 较低。抚养具有高免疫保护需求和营养不良的年轻或男婴的双重负担可能会降低母体 sIgA 向母乳的输送。