HX14 A nutrient missing, a diagnosis misread: pellagra and the cost of malnutrition

Abstract

Pellagra is a nutritional deficiency disease caused by inadequate intake of vitamin B3 (niacin) or its precursor tryptophan. It is classically defined by the ‘four Ds’: dermatitis, diarrhoea, dementia and, if untreated, death. Historically, pellagra flourished in populations dependent on maize-based diets. The disease was first systematically described in 1735 by Gaspar Casal y Julián in Spain, where he documented the characteristic photosensitive dermatitis later termed Casal’s necklace. For nearly two centuries, pellagra remained endemic across southern Europe and the Mediterranean, attracting the attention of physicians who debated whether it was a cutaneous disorder, a toxic exposure or a systemic illness. In Italy, Gaetano Strambio established a dedicated pellagra hospital in Legnago in 1778 and, in his seminal three-volume work De Pellagra (1786–1789) demonstrated that the disease could occur even in the absence of overt dermatitis, arguing against a purely dermatological explanation. Later, Cesare Lombroso proposed that pellagra resulted from a toxin in spoiled maize, a theory that would persist well into the modern era. In the USA, pellagra appeared dramatically in the early twentieth century, first recognized in 1906 by George H. Searcy during an outbreak in Alabama. As the disease spread across the American South, competing explanations emerged, including infectious and hereditary theories, notably endorsed by the Thompson–McFadden Commission in 1912. These views delayed effective intervention. A decisive turning point came in 1914, when Joseph Goldberger of the US Public Health Service demonstrated through meticulous observational and interventional studies that pellagra was not infectious but dietary in origin. His work, later strengthened by field studies with statistician Edgar Sydenstricker, reframed pellagra as a disease rooted in poverty and malnutrition. Goldberger’s findings ultimately paved the way for identification of niacin and food fortification, marking one of the most important public health victories in nutritional medicine.