Pellagra is a nutritional disorder showing a number of nervous, digestive and skin symptoms. It is due to deficiency of the nicotinic acid component of the vitamin B in association with deficiency of protein. It occurs where people live on a diet of maize without adequate first class protein. The cause of the disease lasts many years with digestive disturbances including loss of appetite, diarrhoea or constipation, headache and irritability. The skin symptoms last about 2 weeks and consist of redness, the skin then remains rough, thickened and permanently brownish. For several years the disease may recur in the spring, gradually becoming more severe, with the patient slowly growing emaciated and in some cases completely paralytic or demented.
Pellagra is still prevalent in areas of Africa south of the Sahara where maize is the staple cereal. Once a serious problem in Egypt, it has now largely or completely disappeared. This decline has been mainly due to varied diet containing more wheat and other cereals and less maize. Pellagra has been observed in people eating another cereal, jowar (Sorghum vulgar), especially in the Indian city of Hyderabad. Pellagra continues to be endemic in Mediterranean countries, the Far East, Africa, Mexico and the southern USA; and it can be seen as a complication of chronic alcoholism in any part of the world.