The Vitamin D Workshop is a non-profit educational organization (est. 1977) whose mission is to organize scientific meetings on the metabolism, biological functions, and health effects of vitamin D. The goal of this R13 grant application to support a series of annual Vitamin D Workshops from 2021-2025. To date there have been 22 highly successful international Vitamin D Workshops which have typically attracted 200-300 basic researchers, translational scientists, clinicians, and policy makers from around the globe. Vitamin D is the precursor for an active steroid hormone that activates a nuclear receptor (the Vitamin D receptor, or VDR) to regulate gene expression. Its traditional role is to regulate the biology of cells in the bone, kidney, and intestine to control calcium and bone metabolism. Vitamin D can be obtained through diet and supplements as vitamins D2 and D3, and vitamin D3 can also be synthesized in skin upon exposure to UV light. Both the skin production of vitamin D and the molecular actions controlling calcium metabolism are suppressed by aging. Many studies have associated vitamin D status with a wide variety of physiologic and age-related, pathologic processes, e.g. cancer, diabetes, multiple sclerosis, and inflammatory bowel disease. While this research has generated considerable media attention, it has also led to many new questions about the molecular actions of the vitamin D hormone, the challenges of assessing vitamin D status and the optimal intake to prevent chronic diseases. It is not clear how aging, ethnicity and genetics influence vitamin D actions, and how requirements are altered in diverse populations. These issues are of great interest to scientists, health professionals and the general public. Collectively, these factors justify an annual meeting of vitamin D scientists to share research ideas and resources, discuss the emerging basic and applied data, and bring areas of controversy to light. The Specific Aims of the Vitamin D Workshops are: 1. To conduct a series of scientific conferences on the biology and health-relevant applications of vitamin D that address: • The latest peer-reviewed scientific research regarding the production, metabolism and mechanisms of action of vitamin D as they relate to physiologic state and age. • The concern of worldwide vitamin D deficiency across age groups as well as how to best identify, treat and prevent this condition in different populations and age groups. • The evidence on the adequate and safe levels of vitamin D intake and supplementation for individuals throughout the life course and in those with various age-related chronic disease states. • State of the art research approaches for studying vitamin D. 2. To bring together an interdisciplinary group of scientists from academia, medicine, industry, government and grassroots organizations with common interests in scientifically examining the health effects of vitamin D. 3. To encourage and recognize early-stage, minority and disadvantaged investigators conducting research on vitamin D and facilitate their interactions with established investigators through provision of scholarships, travel grants and young investigator awards. 4. To disseminate outcomes of the workshop through publication of the Conference Proceedings.

Vitamin D Workshops are international scientific conferences on the biology and health implications of vitamin D. This R13 will support five years of annual conferences to include invited talks, keynote lectures, oral communications, and poster presentations.