Pellagra, puh LAG ruh or puh LAY gruh, is a disease caused by a lack of niacin and other B-complex vitamins (see Vitamin). This disease became widespread after the Spaniards introduced corn into Europe from Central America in the early 1700's. Corn is a poor source of niacin, and many people who ate corn as the main part of their diets developed pellagra. For more than 200 years, pellagra was common in areas of the world where people ate mostly corn. In the early 1900's, the American physician Joseph Goldberger proved that pellagra was associated with the diet (see Goldberger, Joseph).