Pellagra is not a vitamin, it's a disease.

It can be classed as either primary or secondary pellagra. Primary pellagra is typically caused by insufficient levels of dietary niacin, also known as vitamin B3 (exogenous production) or of the amino acid tryptophan, from which the body synthesizes niacin (endogenous production). It may result from decreased dietary intake, decreased nutrient absorption or increased nutritional requirements, or a combination of these factors. It may occur secondary to alcoholism, chronic gastrointestinal disease, carcinoid syndrome, or Hartnup disease, amongst a range of other conditions. Secondary pellagra is due to impaired amino acid conversion.

Pellagra is also frequently seen amongst populations that consume large quantities of corn and minimal animal protein, as corn is low in both niacin and biologically available tryptophan.

Catherine Convery Walsh

Registered Dietitian

MSc Human Nutrition and Metabolism, University of Aberdeen Medical School