 Those whose diet consisted mostly of corn meal often became sick — because of the lack of niacin and tryptophan — with the deficiency disease pellagra, which was common in Spain, Northern Italy, and the southern United States.In Mexico, particularly in the towns and cities, corn tortillas are often made nowadays by machine and are very thin and uniform, but in many places in the country, they are still made by hand, even when the "nixtamal" is ground into masa by machine.In Belize, El Salvador, Guatemala, or Honduras, they are still often made by hand and are thicker.