Start Date: Mar 16, 2009
End Date: Mar 15, 2014
LAB: Bone Health The Bone Metabolism Laboratory uses a variety of approaches to carry out its clinical and translational research program. Observational studies such as the publicly available cross-sectional National Health and Nutrition Examination Survey will be used to examine associations of vitamin D with bone mineral density. Longitudinal cohort studies, such as the Nurses Health Study, will be used to link vitamin D levels to risk of several chronic diseases. We will employ diet-controlled metabolic studies to define address several research goals. For example, we will examine the impact of a dietary alkaline load on muscle tissue changes and on indices of bone metabolism in healthy older subjects on both low and high protein diets. Information learned from this metabolic study will be helpful in the design of a large randomized controlled trial to determine the long term effects of lowering the dietary acid load on muscle performance and mass and on rates of bone turnover and bone loss. The Bone Metabolism Laboratory has a strong network of collaborations, both internal, exemplified by our work on multiple projects with the Nutrition, Exercise Physiology and Sarcopenia Laboratory, and external. These collaborations allow us to expand our reach to examine the effect of vitamin D on risk of other chronic diseases such as periodontal disease and diabetes. They also allow us access to basic research technologies, such as gene array analysis, that enable us to identify mechanisms by which nutrients affect bone and muscle. LAB: Vitamin K Laboratory analysis of different forms of vitamin K will be conducted in selected foods obtained through collaboration with the USDA Nutrient and Data Laboratory (NDL), as part of the Food and Nutrient Analysis Program. Priorities for food analysis will include dietary supplements, food purchased in family style restaurants, foods common to the Hispanic/Latino diet, and foods associated with high calorie diets. Food composition data will be transferred to the NDL for entry into national food composition databases. To identify dietary and non-dietary factors that determine how much vitamin K obtained from foods is utilized, we will apply stable isotope techniques to measures of vitamin K metabolism. Data obtained from ongoing metabolic studies in men and women, in addition to pilot feasibility studies, will be used to refine the study design to test the response of these measures to intake of different vitamin K-rich food sources. Animal models will be used to identify tissue-specific effects of interactions between vitamin K and other fat-soluble vitamins, with an emphasis on vitamins A and D. To identify mechanisms of action for vitamin K other than its classic role as an enzyme cofactor, urinary and serum levels of vitamin K metabolites will be measured in response to vitamin K supplementation using archived samples from human and animal studies. We will then focus on the role of different forms of vitamin K in inflammation through the inactivation of nuclear receptors in macrophages.