McCollum, Elmer Verner (1879-1967), a United States physiological chemist. McCollum was one of the discoverers of vitamins A, B, and D, between the years 1912 and 1922. McCollum was born near Fort Scott, Kansas. In 1906 he received a Ph.D. from Yale University. He taught at the University of Wisconsin, 1907-17, and was professor of biochemistry at Johns Hopkins University, 1917-44.