A deadly Southern epidemic was blamed on germs. The real cause was diet.
In the early 1900s pellagra, a disease of rashes, diarrhoea and dementia, swept the American South and affected some 3 million people. Most experts suspected a germ or toxic corn. Joseph Goldberger showed it was a poverty diet, and later work pinned it on a missing vitamin: niacin.
Pellagra is classically summed up by the 'four Ds': dermatitis, diarrhoea, dementia and, if untreated, death. Skin exposed to the sun becomes inflamed and later darkens and peels. It was first described in Spain in 1735, became endemic in northern Italy, and by the 1880s affected over 100,000 Italians. Because it clustered where maize was the staple crop, many, including Cesare Lombroso, blamed a toxin in the corn; others suspected an insect carrier, as with malaria.
In the United States, pellagra was first reported in 1902 and then exploded across the South. Between 1906 and 1940, more than 3 million Americans were affected and over 100,000 died, which by one account makes it the deadliest nutrition-related disease in American history. In 1915 the Public Health Service put Joseph Goldberger on the case. He noticed that in orphanages it struck children aged 6 to 12 but not older or younger ones, and in asylums it struck patients but not doctors or nurses. That pattern pointed to food rather than infection.
Goldberger changed the food in these institutions, adding fresh meat, milk and legumes, and showed pellagra could be prevented. He then had 11 volunteer prisoners in Mississippi eat a monotonous diet of grits, biscuits, syrup and other cheap staples; within five months, six developed its telltale rash. He argued that the root cause was poverty, as cotton farming crowded out varied food, and that social reform would end it. A 2017 study supported this: pellagra fell where boll weevils forced farmers to swap cotton for food crops.
Goldberger never identified the missing nutrient. In 1937 Conrad Elvehjem showed that niacin, vitamin B3, cured a pellagra-like disease in dogs, and it was soon shown to cure people too. Food fortification followed, and by the 1950s pellagra had virtually vanished from the US. The Native American farmers who first domesticated maize had long avoided it by nixtamalization, treating the grain with an alkali such as lime, which makes its niacin available.
Source: Wikipedia — Pellagra · Text summarised from Wikipedia (CC BY-SA 4.0)
