See D. A. Roe, A Plague of Corn: A Social History of Pellagra (1973).
Pellagra is an endemic disease 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.
Tryptophan is an essential amino acid found in soybeans, meat, poultry, fish, and eggs. If one's diet contains these foods, one's need for niacin from other sources will be reduced.
The relationship between leucine and pellagra is unclear.
The main results of pellagra can easily be remembered as "the four D's": diarrhea, dermatitis, dementia, and death.
Frostig and Spies (acc. to Cleary and Cleary) described psychological symptoms of pellagra:
The elementary syndrome:
Pellagra can be treated with niacin (usually as niacinamide). The frequency and amount of niacinamide administered depends on the degree to which the condition has progressed.
The traditional food preparation method of corn, nixtamalization, by native New World cultivators who had domesticated corn required treatment of the grain with lime, an alkali. It has now been shown that the lime treatment makes niacin nutritionally available and reduces the chance of developing pellagra. When corn cultivation was adopted worldwide, this preparation method was not accepted because the benefit was not understood. The original cultivators, often heavily dependent on corn, did not suffer from pellagra. Pellagra became common only when corn became a staple that was eaten without the traditional treatment.
Pellagra was first described in Spain in 1735 by Gaspar Casal, who published a first clinical description in his posthumous "Natural and Medical History of the Asturian Principality" (1762). This led to the disease being known as "Asturian leprosy", and it is recognized as the first modern pathological description of a syndrome(1). It was an endemic disease in northern Italy, where it was named "pelle agra" (pelle = skin; agra = rough) by Francesco Frapoli of Milan. Because pellagra outbreaks occurred in regions where maize was a dominant food crop, the belief for centuries was that the maize either carried a toxic substance or was a carrier of disease. It was not until later that the lack of pellagra outbreaks in Mesoamerica, where maize is a major food crop (and is processed), that the idea was considered that the causes of pellagra may be due to factors other than toxins.
In the early 1900s, pellagra reached epidemic proportions in the American South. There were 1,306 reported pellagra deaths in South Carolina during the first ten months of 1915; 100,000 Southerners were affected in 1916. At this time, the scientific community held that pellagra was probably caused by a germ or some unknown toxin in corn. The Spartanburg Pellagra Hospital in Spartanburg, South Carolina, was the nation's first facility dedicated to discovering the cause of pellagra. It was established in 1914 with a special congressional appropriation to the U.S. Public Health Service (PHS) and set up primarily for research. In 1915, Joseph Goldberger, assigned to study pellagra by the Surgeon General of the United States, showed that pellagra was linked to diet by inducing the disease in prisoners, using the Spartanburg Pellagra Hospital as his clinic. By 1926, Goldberger established that a balanced diet or a small amount of brewer's yeast prevented pellagra. Skepticism nonetheless persisted in the medical community until 1937, when Conrad Elvehjem showed that the vitamin niacin cured pellagra (manifested as black tongue) in dogs. Later studies by Tom Spies, Marion Blankenhorn, and Clark Cooper established that niacin also cured pellagra in humans, for which Time Magazine dubbed them its 1938 Men of the Year in comprehensive science.
In the research conducted between 1900-1950, it was found that the number of cases of women with pellagra was consistently double the number of cases of afflicted men. This is thought to be due to the inhibitory effect of estrogen on the conversion of the amino acid tryptophan to niacin. It is also thought to be due to the differential and unequal access to quality foods within the household. Some researchers of the time gave a few explanations regarding the difference. As primary wage earners, men were given consideration and preference at the dinner table. They also had pocket money to buy food outside the household. Women gave protein quality foods to their children first. Women also would eat after everyone else had a chance to eat. Women also upheld the triad of maize, molasses and fat back pork which combine to contribute to cause pellagra.
Gillman and Gillman related skeletal tissue and pellagra in their research in South African Blacks. They provide some of the best evidence for skeletal manifestations of pellagra and the reaction of bone in malnutrition. They claimed radiological studies of adult pellagrins demonstrated marked osteoporosis. A negative mineral balance in pellagrins was noted which indicated active mobilization and excretion of endogenous mineral substances, and undoubtedly impacted the turnover of bone. Extensive dental caries were present in over half of pellagra patients. In most cases caries were associated with "severe gingival retraction, sepsis, exposure of cementum, and loosening of teeth".