Dietary and Hormonal Factors in Relation to Physical Function

Physical function is increasingly recognized as a key component of healthy aging, in particular as a core component of mobility and independent living in older adults. Prior research has also demonstrated that poor physical function is related to hospitalization, long-term nursing home care, and increased mortality among older adults. Women appear to have a greater burden of physical function impairment, although it is not certain whether this is due to gender differences in reporting of impairments, risk factor differences, or biologic differences. In this dissertation, I examined not only risk factors for development of physical function impairment, but also explanations for apparent gender differences. First, while diet is related to numerous chronic diseases and conditions of aging, limited research has examined the role of diet, which may be an important strategy to prevent or delay decline in physical function with aging. In Chapter 1, I prospectively examined the association between the Alternative Healthy Eating Index-2010 (AHEI-2010), a measure of diet quality, with incident impairment in physical function among 54,762 women from the Nurses’ Health Study. Overall, participants in higher quintiles of the AHEI-2010, indicating a healthier diet, were less likely to have incident physical impairment versus participants in lower quintiles over the 18 year follow-up period. There are established sex differences in later life physical function, with a greater number of impairments in function and steeper rates of decline observed among women compared to men. It is hypothesized that some of the differences could be due to women’s greater likelihood to report symptoms compared to men. Few prospective studies have investigated possible risk factor differences or differences in biological factors between men and women. In Chapter 2, I present the findings from an analysis investigating sex differences in relation to physical function decline. Overall, women had lower physical function scores at baseline and steeper rates of decline compared to men. These differences were partially explained by the difference in risk factors between men and women, indicating that it could be of particular importance to intervene on risk factors in women to prevent further physical function impairments with aging.