 Soon after, a generation of children grew up on cod-liver oil, and rickets was virtually wiped out.Harry Day, a colleague and McCollum biographer, writes that finding vitaminD was the work of "a host of investigators" but that McCollum and his group did "much of the groundwork".Kenneth Carpenter, professor emeritus at the University of California, Berkeley, writes in his article "The Nobel Prize and the Discovery of Vitamins" that "strangely" McCollum was not nominated for a Nobel Prize.