Pellagra is a disease that is caused by a deficiency of niacin (B3) and protien, and results in skin rashs, G.I. distress and nervous tics, and eventually dementia and death.
Up until the early 20th century, pellagra was thought to be due to germs, and was common in Southren U.S. orphanges and asylums, where it was known as "the Southern scourge." In 1915, a doctor, Joseph Goldberger, believed pellagra was due to a diet deficiency when he realized pellagra only effected the orphans and patients, who were fed a limited diet consisting mostly of corn, and not their caretakers. He was allowed to conduct a 6 month experienment on prisoners, where they was fed a diet primarily of corn, without any meat, milk or vegetables. Even though the prisoners developed pellagra and were likewise cured onced their diet was corrected, the medical community laughed at Goldberger's findings. It would be over 20 more years before pellagra was widely recognized as due to poor diet and not germs, when researchers Spies, Cooper and Blankenhorn (and not Goldberger) were honored for establishing the link between pellagra and niacin.