Roger J. Williams, 94, a leading authority on nutrition. Williams, a professor emeritus at the University of Texas, discovered and isolated pantothenic acid, one of the "universal vitamins" required by all living cells. He founded the university's Clayton Foundation Biochemical Institute, where researchers discovered more vitamins and their variants than did those at any other research facility in the world. Williams was a proponent of the theory of "biochemical individuality," that individual nutritional requirements vary because no two people are exactly alike physiologically. He retired in 1985. In Austin, Tex., on Saturday.