Niacin and the Black Tongue
In the early twentieth century, an epidemic of pellagra, or Black Tongue, arose in the southern US states of North Carolina and surroundings.
The symptoms were diarrhoea, mental confusion, loss of weight, weakness, irritation in the mouth and stomach linings, and lesions of the skin. Skin, especially that which was exposed to the sun, would become dark, thick, and scaly. The disease was sometimes misdiagnosed as leprosy. Sometimes the mental confusion would lead to depression, irrational violence, or lethargy.
Pellagra symptoms in the hands
Two out of every three people affected died.
In 1914 in North Carolina, there were 551 deaths recorded. There were 831 in 1915.
After experimentation on prisoners, mentally ill people, and orphan children (yes, in the twentieth century), it was discovered that certain foods could cure the issue.
As is usual in an epidemic, deaths will rise for a while after discovery of the cure, until the cure can be explained and disseminated properly, so it took a while to reduce the deaths to 0 nationally. The outbreak of various wars (when is the US not at war?) and a major economic depression made it difficult as well. The first year that no-one died of pellegra in the US was 1960.
In 1914, the primary diet of North Carolina and neighbouring states was mostly corn-based, with little variation, because corn was easy to grow and very cheap.
After years of experimentation, it was finally discovered that the nutrient that people were missing from their diets was niacin.
Niacin had already been discovered in 1837 by chemist Hugo Weidel, who created it by oxidising nicotine with nitric acid. Called nicotinic acid at the time, its nutritional use was not recognised until in 1937, biochemist Conrad Elvehjem was looking for what he called the “pellegra-prevention factor” or “anti-blacktongue factor”, and finally found nicotinic acids in livers and yeast. After experimentation on dogs and chickens, he verified that this was the cure for pellegra.
Niacin is actually present in corn, but it cannot be extracted easily. In fact, it was discovered in 1951 that it can only be released from corn by using extremely lime water with a pH of 11.
The recommended daily amounts for niacin are 16mg for males, and 14mg for females. 35mg will give you a "niacin flush", where the face or upper body turns red and feels like it is burning.
Very high doses can cause liver damage, but the damage will usually revert when if the level of niacin is brought down to the RDA. Overdosing at a 1-6g level can have a side-effect of lowering cholesterol, though, and this is used in treatment for hypercholesterolemia.