"Epidemiology Pellagra can be common in people who obtain most of their food energy from maize (often called "corn"), notably rural South America where maize is a staple food. Maize is a poor source of tryptophan as well as niacin if it is not nixtamalized. Nixtamalization of the corn corrects the niacin deficiency, and is a common practice in Native American cultures that grow corn. Following the corn cycle, the symptoms usually appear during spring, increase in the summer due to greater sun exposure, and return the following spring. It may even have been known as Spring Sickness in the American South, according to the movie The Southerner (1945). Indeed, pellagra was once endemic in the poorer states of the U.S. South, like Mississippi and Alabama, as well as among the inmates of jails and orphanages as studied by Dr. Joseph Goldberger. Pellagra is common in Africa, Mexico, Indonesia, and China. In affluent societies, a majority of patients with clinical pellagra are poor, homeless, alcohol dependent, or psychiatric patients who refuse food. It was common amongst prisoners of Soviet labor camps, the infamous Gulag. It can be found in cases of chronic alcoholism. In addition, pellagra is a micronutrient deficiency disease that frequently affects populations of refugees and other displaced people due to their unique, long-term residential circumstances and dependence on food aid. Refugees typically rely on limited sources of niacin provided to them, such as groundnuts; the instability in the nutritional content and distribution of food aid can be the cause of pellagra in displaced populations." Source and further information: http://en.wikipedia.org/wiki/Pellagra

Yes,in less developed countries where maize is a staple of poorer people. Also found in alcoholics. Lack of niacin.

Nice color?

in some places, yes