A deficiency of nicotinamide is known as pellagra, a disorder characterized by skin sores, gastrointestinal problems, and mental aberrations. In the early stages of pellagra, sufferers become unusually sensitive to light and may form what first appears to be serious sunburn. This general reddening of the skin soon takes on the form, however, of scaly, reddish brown lesions. Confusion, depression, delirium and other neurological symptoms tend to occur most often in the later stages of the condition. Pellagra is relatively rare in many parts of the world, but in areas where corn, a food that does not contain nicotinamide or tryptophan, is the chief component of the diet, it is more common. The nutritional disorder is also sometimes a side effect incurred by chronic alcoholics.