William B. Grant, Ph. D. (born 1942) is considered one of the world's leading vitamin D experts. After completing his doctorate at the University of California, Berkeley, the physicist devoted himself in particular to researching the epidemiology of chronic diseases as a function of sun exposure. Through his work on the connection between vitamin D and cancer, numerous tumors have been identified whose development or growth can be influenced by vitamin D. Dr. Grant heads the Sunlight, Nutrition and Health Research Center (SUNARC) in San Francisco (USA).