Vitamins from A to K In the 1930s André and Marguerite Lwoff showed all organisms use the same vitamins and coenzymes. This was just one chapter in the story of our understanding of vitamins, compounds that the body needs only in small amounts but that are very important to good health. In the 1700s British naval doctors learned that eating citrus fruits helped prevent scurvy, but it wasn’t until 1932 that Albert Szent-Györgyi (1893–1986) discovered that ascorbic acid, vitamin C, is the vital compound in citrus fruits that stops scurvy. Vitamin B1, whose deficiency causes beriberi, was discovered by Robert R. Williams (1886–1965) in 1925. Vitamin K, important to blood clotting, was discovered in the 1930s following an outbreak of fatal bleeding among cattle that were fed on rotten sweet-clover hay, deficient in the vitamin. In 1957 Dorothy Crowfoot Hodgkin (1910–1994) determined the molecular structure of vitamin B12 using X-ray crystallography.