Good sources of niacin
Fish and meat are particularly rich in niacin, but eggs, wholemeal products, pulses, vegetables and fruit also contribute to the niacin supply. However, plant-derived niacin cannot be absorbed as well as animal-based niacin. The good news is that niacin is relatively stable in heat, light and air. Only about 20% is lost during cooking. As niacin is composed of an amino acid (tryptophan), you are generally safe with products rich in protein.
Probably the best know deficiency disease is pellagra, something like “rough skin”. Pellagra was recognised in the 18th century, in regions where maize and millet were dominant food crops, both of them containing only little natural niacin. Even today, these skin diseases are common in Third World countries. In affluent societies, pellagra does not occur anymore.
A deficiency may lead to sleep disturbances and digestive disorders. First signs may show up as a lack of appetite, combined with a dry mouth and weight loss. Dizziness, headache and slight confusion may occur.