In the early 1900s, scientists noticed that certain foods prevented diseases like scurvy, rickets, and beriberi. When it became obvious that vitamins, organic compounds that the body needs but can’t make itself, were responsible, researchers went on a hunt to classify them all. Cornelia Kennedy, a master’s student at the University of Wisconsin, suggested categorizing them with the alphabet. Soon, about half the alphabet was assigned a vitamin. The problem? Many weren’t vital to human life. Vitamin J, for example, only helped guinea pigs. Vitamin L was good for making rats lactate. Vitamin P didn’t help humans much, but it did give flower petals their pretty colors. So those “vitamins” were kicked off the list. Others, like vitamins H and I, were later reassigned to the B complex. The purge left vitamin K standing awkwardly all by itself.