Pellagra, a niacin deficiency disease, begins unremarkably, usually with weakness, skin rash, mouth sores, and loss of appetite. Unless checked, however, it gradually worsens, producing severe inflammation of the skin, mental disturbances, and diarrhea--followed all too often by death. The word pellagra is Italian for "rough skin," a description of the rough, scaly skin seen in most pellagra patients.

The disease was first noticed by scientists in Europe around 1720, just about the time that maize (or Indian corn) was beginning to be heavily imported from the Americas and planted in many countries. In 1735, the symptoms of pellagra were described by Spanish physician Gaspar Casal (1679-1759), who correctly observed that the disease seemed to be associated with maize-based diets. At the time, however, most scientists believed the disease was caused by a toxin somehow produced by maize, particularly by wet or spoiled maize, and spent many wasted years hunting...