Protein energy nutrition and long-term change in muscle and fat mass: A case study of urbanization-related change among healthy elderly mainland Chinese.

摘要

Rapid population aging in China promises to stress limited health and social service infrastructure. To cope with this 'demographic time bomb', strategies are urgently needed to promote the active life expectancy of older adults in China. Although preventing adverse changes in body composition would seem an obvious strategy to prevent morbidity and functional decline, effective approaches for realizing this strategy are not clear. The role of diet---and concurrent urbanization-related dietary change---is particularly unclear, despite clear links between urban residence, dietary intake and short-term change in body composition.; This study used longitudinal data on 608 healthy, non-obese Chinese (50--70y) from the China Health and Nutrition Surveys to explore whether diet and urbanization-related dietary change might be strategic variables for long-term health promotion. The study tested for evidence of long-term counterparts to the well-established short-term associations between diet and changes in body composition. The project involved three specific aims, to describe the prevalence and correlates of patterns of long-term change in arm muscle and body fat, determine if protein and energy intakes explain the observed patterns of change in body composition, and, lastly, to examine the implications of urbanization-related changes in dietary intake.; The results indicate that diet may be an important determinant of long-term changes in body composition. Consistent with known short-term relationships between diet and change in body composition, particular profiles of protein and energy intake predicted all possible combinations of long-term change in arm muscle and body fat for this sample of older adults. Higher energy intakes were associated with gain of body fat for both sexes. Sex-specific, nonlinear relationships were observed between protein and energy intake and change in arm muscle.; The results also indicated that, as a determinant of long-term changes in body composition, diet may mediate effects of urbanization on the health and functional status of older adults in China. Associations between level of urbanization and changes in body composition paralleled the observed associations between level of urbanization and protein and energy intake. Together the results suggest that diet may emerge as a clear target for public health intervention.