Elmer Verner McCollum (March 3, 1879 – November 15, 1967) was an American biochemist known for his work on the influence of diet on health. McCollum is also remembered for starting the first rat colony in the United States to be used for nutrition research. His reputation has suffered from posthumous controversy. Time magazine called him Dr.Vitamin. His rule was, "Eat what you want after you have eaten what you should." Living at a time when vitamins were unknown, he asked and tried to answer the questions, "How many dietary essentials are there, and what are they?" He and Marguerite Davis discovered the first vitamin, namedA, in 1913. McCollum also helped to discover vitaminB and vitaminD and worked out the effect of trace elements in the diet. As a worker in Wisconsin and later at Johns Hopkins, McCollum acted partly at the request of the dairy industry. When he said that milk was "the greatest of all protective foods", milk consumption in the United States doubled between 1918 and 1928. McCollum also promoted leafy greens, which had no industry advocates. McCollum wrote in his 1918 textbook that lacto vegetarianism is, "when the diet is properly planned, the most highly satisfactory plan which can be adopted in the nutrition of man". Family and education McCollum's ancestors immigrated to the United States from Scotland in 1763. McCollum was born in 1879 to Cornelius Armstrong McCollum and Martha Catherine Kidwell McCollum on a farm from Redfield, Kansas, usually reported to have been Fort Scott, Kansas, which was away. His parents had little education but became relatively well-off by local standards. He spent his first seventeen years on this farm and attended a one-room school. He had one brother, Burton, and three sisters. At some point he had surgery for a detached retina, which the doctors were unable to "glue back again". His father suffered from tuberculosis. His mother, who had only two winters of schooling but was devoted to her children's education, took McCollum and his brother to the 1893 World's Columbian Exposition. All three of his sisters graduated from Lombard University and married Universalist ministers. A lifelong close friend of his brother's, Burton became a geophysicist who helped to pioneer the use of sound waves in oil drilling. In 1896 his mother moved their family to Lawrence, Kansas, where they hoped to profit from a fruit farm adjoining the University of Kansas.