1. Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University , Boston MA , USA
2. Department of Aging Medicine and Aging Research, University of Zurich, and City Hospital Zurich-Waid , Zurich , Switzerland
3. Vitamin D Standardization Program (VDSP) , Havre de Grace, MD , USA
4. The Saban Research Institute at Children’s Hospital Los Angeles , Los Angeles, CA , USA
5. Division of Endocrinology, Tufts Medical Center , Boston MA , USA