Infant Growth, Milk Composition, and Maternal Energetics in a High Altitude Environment

在人类历史的绝大多数时期，母乳一直是婴儿期营养素的主要来源。最近的研究表明，母乳是一种非常复杂的液体，含有丰富的常量营养素，免疫因子和激素成分，所有这些都可以喂给婴儿。同样，母乳的变化也令人难以置信，不同社会和生活环境中的妇女产生的这些成分的数量也不同。尽管有越来越多的研究，但仍然有很多东西需要了解牛奶在不同的生态环境中如何以及为什么会发生变化，以及这些差异如何影响婴儿的健康和成长。这项研究需要一个详细的人口生活在高海拔环境的Nubri山谷，尼泊尔，调查母乳如何可能参与调节婴儿的生长在相当大的生态压力。该项目将为本科生和研究生的研究和培训提供机会，并促进研究地点的区域健康和科学教育。了解生态压力（如海拔和寒冷压力）如何影响母乳成分，进而影响婴儿代谢和生理发育，对于了解工业化和快速工业化人群中超重和代谢功能障碍的风险因素可能至关重要。鉴于母乳在婴儿期的主要作用，母乳成分可能存在相当大的自然选择，这本身就是一个选择的关键时期。在牛奶中发现的生长因子和代谢激素显示出与线性生长、体重增加、无脂肪质量和年龄大小的显著相关性，使得牛奶产生的激素和细胞因子可能成为婴儿身体组成发育规划的候选者。然而，这些协会从来没有被调查在一个生态压力的人口环境选择婴儿表型可能是严重的。该项目将调查来自喜马拉雅山Nubri山谷（尼泊尔）9个村庄的115对母婴的生态、产妇生理、乳汁成分和婴儿生长发育之间的关系。人口是藏族，家族史记录了从西藏高原移民后至少700人在山谷中居住。村庄的海拔高度从7，500英尺到13，100英尺不等。在婴儿出生后第一年的四个时间点收集母乳样本、代谢测试和体温扫描。母亲和孩子的热成像是一项创新，它将显示身体脂肪模式的差异。此外，将从出生时开始和出生后每隔两个月收集母亲的访谈和母亲和儿童的人体测量数据（身高、体重、身体成分）。 由此产生的数据将提供有史以来收集到的最完整的图片，其中包括第一年生命中与海拔和季节相关的生长，乳汁激素和母体生殖条件差异。

For the vast majority of human history, breast milk has been the primary source of nutrients during infancy. Recent research has shown human milk to be a tremendously complex fluid containing a wealth of macronutrients, immune factors and hormonal components, all of which get fed to the baby. Similarly, mothers' milk is incredibly variable, with women in different societies and living situations producing different amounts of many of these components. Despite a growing body of research, there is still much left to understand about how and why milk varies in different ecological circumstances and how these differences may affect the health and growth of infants. This study takes a detailed look at a population which lives in the high altitude environment of the Nubri Valley, Nepal, to investigate how breast milk may be involved in the regulation of infant growth under considerable ecological stress. The project will provide opportunities for undergraduate and graduate student research and training, and facilitate regional health and science education at the study location. Understanding how ecological pressures such as altitude and cold stress influence human milk composition and in turn, infant metabolism and physiological development, may be crucial in understanding the risk factors for overweight and metabolic dysfunction in industrialized and rapidly industrializing populations.It is likely that there has been considerable natural selection on human milk composition given the primary role human milk has during infancy, itself a critical period of selection. Growth factors and metabolic hormones found in milk show significant associations with linear growth, weight gain, fat free mass, and size for age, making milk born hormones and cytokines likely candidates for developmental programming of infant body composition. However, these associations have never been investigated in an ecologically stressed population where environmental selection on infant phenotypes may be severe. This project will investigate associations between ecology, maternal physiology, milk composition, and infant growth and development in 115 mother-infant pairs from nine villages in the Nubri Valley of the Himalayas (Nepal). The population is ethnically Tibetan, with family histories recording occupation in the valley for at least 700 hundreds following immigration from the Tibetan plateau. Villages range in altitude from 7,500-13,100 feet above sea level. Milk samples, metabolic tests, and thermal body scans will be collected at four time points over the first year of infant life. The thermal imaging of mother and child is an innovation which will show differences in body fat patterning. Additionally, interviews of the mothers and anthropometric measurements (height, weight, body composition) of both mother and child will be collected beginning at birth and at two month intervals afterward. The resulting data will provide the most complete picture ever collected of altitude- and seasonality-associated differences in growth, milk hormones, and maternal reproductive condition across the first year of life.