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Background: Ethnographic work among high altitude populations has shown that children are highly mobile—the most recent expression of this is the educational migration of children born at high altitude to boarding schools at lower altitudes. The impact of these patterns of migration on size for age are unknown. Aim: We investigated the association between growth in weight and height and educational migration in ethnic Tibetan children living in and out of their natal communities. Subjects and methods: Five hundred and fifty eight children ages three to sixteen from the Nubri Valley, Nepal participated in this study. Three hundred children were living in natal villages and 258 were attending boarding schools in Kathmandu. Height, weight, and skinfold thicknesses were collected and matched to demographic data from the community. Results: There was no association between altitude of family residence and size for age z‐scores. Males had lower z‐scores than females; z‐scores for both groups declined with age. Differences in size for age among children in boarding schools were associated with two factors: sex and type of boarding school (individual sponsor or group funded). Individuals attending individually sponsored schools had greater size for age compared to children in group funded schools or in their natal villages; younger children in collectively funded schools were smaller than village peers. Conclusions: Despite popular perceptions, educational outmigration in Himalayan communities may not be associated with improved child growth outcomes and investment in community level schools may be a practical solution for improving child growth and physical and mental health. [ABSTRACT FROM AUTHOR]

Objectives: Connecting traits to biological pathways and genes relies on stable observations. Researchers typically determine traits once, expecting careful study protocols to yield measurements free of noise. This report examines that expectation with test–retest repeatability analyses for traits used regularly in research on adaptation to high‐altitude hypoxia, often in settings without climate control. Methods: Two hundred ninety‐one ethnic Tibetan women residing from 3500 to 4200 m in Upper Mustang District, Nepal, provided three observations of hemoglobin concentration, percent of oxygen saturation of hemoglobin, and pulse by noninvasive pulse oximetry under conditions designed to minimize environmental noise. Results: High‐intraclass correlation coefficients and low within‐subject coefficients of variation reflected consistent measurements. Percent of oxygen saturation had the highest intraclass correlation coefficient and the smallest within‐subject coefficient of variability; measurement noise occurred mainly in the lower values. Hemoglobin concentration and pulse presented slightly higher within‐subject coefficients of variation; measurement noise occurred across the range of values. The women had performed the same measurements 7 years earlier using the same devices and protocol. The sample means and SD observed across 7 years differed little. Hemoglobin concentration increased substantially after menopause. Conclusions: Analyzing repeatability features of traits may improve our interpretation of statistical analyses and detection of variation from measurement or biology. The high levels of measurement repeatability and biological stability support the continued use of these robust traits for investigating human adaptation in this altitude range. [ABSTRACT FROM AUTHOR]

Objectives: Rapid socioeconomic change, associated with development and a growing tourism industry is occurring across the Himalayas. The health impact of this rapid economic development is poorly understood, especially for infants and young children. This study investigated the associations between village level economic differences as indexed by economic development and tourism engagement on infant and young child growth and health in a population of ethnic Tibetans living in the western Himalayas of Nepal. Methods: One hundred and fifty nine infants and young children (ages 1‐24 months) were enrolled. Anthropometric data (height, weight, triceps skinfold thickness) were collected at a single time point. Village level measurements of tourism and market engagement were incorporated into a scale measuring tourism, healthcare, trail access, agriculture, and involvement in medicinal trade. Village level disease patterns were calculated from morbidity and mortality recalls collected since 2003. Results: There were no significant associations between infant weight for age z‐score (WAZ), length for age z‐score (LAZ), or weight‐for‐length for age z‐score (WLZ) and village altitude, village economic development score, or engagement in tourism. Males had significantly higher LAZ, WAZ, and WLZ compared to females; only females showed a decline in LAZ with age. Triceps skinfold thickness z‐score (ZTSF) was inversely associated with village level economic development score in male but not female infants; females ZTSF was positively associated with IYC age. Conclusions: While overall size for age indices (WAZ, LAZ, WLZ) were not associated with altitude or village economic development in this population, ZTSF was inversely associated with village economic development in males but not females. [ABSTRACT FROM AUTHOR]

Objectives: This study explores the acute endocrine reactivity of testosterone and cortisol in women engaging in everyday physical activity in a high altitude environment., Methods: Data were collected from 35 women living in the Himalayas, with women recruited from both high (>10 000 ft.) and low altitude villages (<10 000 ft.). Saliva samples were collected at 3 time points (pre-activity, 30 and 60 minutes) and women wore the wGT3X-BT Actigraph during an hour of everyday work to assess the relationship between high altitude, endocrine reactivity, and physical activity. Saliva samples were then analyzed for testosterone and cortisol., Results: Women living at high altitude had lower cortisol and testosterone levels, after controlling for moderate-to-vigorous physical activity, age, and sum of skinfolds., Conclusions: Testosterone and cortisol increase allocation of energy to costly somatic tissues and the utilization of stored energy. Lower production of these hormones may be beneficial for heightened energetic demands at high altitude., (© 2018 Wiley Periodicals, Inc.)

Objective: The physiological challenges of high altitude have led to population-specific patterns of adaptation. These include alterations to child growth and reproduction, including lactation. However, while breastfeeding has been investigated, nothing is known about milk composition in high altitude adapted populations., Materials and Methods: Here, we investigate milk macronutrient composition, volume, and energy in a sample of 82 Tibetans living at high and low altitude in rural villages (Nubri Valley, Nepal) and at low altitude in Kathmandu, Nepal. Milk samples were collected in the morning using hand expression, frozen, and assayed for fat, protein, and total sugars. Reproductive histories and health recalls were also collected., Results: Milk fat averaged 5.2 ±2.0 g/100 mL, milk sugar 7.37 ± 0.49 g/100 mL, and milk protein 1.26 ± 0.35 g/100 mL for a mean energy density of 81.4 ± 17.4 kcal/100 mL. There were no associations between altitude of residence and milk composition; however, overall milk fat was high compared to reference populations. Within the three groups, milk fat was positively associated with infant age (B = 0.103; p < 0.001) and maternal triceps skinfold thickness (B = 0.095; p < 0.01) while milk sugar was significantly and inversely associated with maternal parity and triceps skinfold thickness., Discussion: Milk fat, and consequently milk energy, may be increased in high-altitude adapted Tibetans when compared to populations living at low altitude. The association between milk fat and maternal adiposity suggests that milk composition may be sensitive to maternal adiposity in this sample, likely reflecting increased metabolic costs of producing a high-fat milk., (© 2015 Wiley Periodicals, Inc.)