Pellagra
When maize was first introduced outside of the Americas it was generally welcomed with enthusiasm
by farmers everywhere for its productivity. However, a widespread problem of malnutrition soon arose wherever maize was introduced. This was a mystery since these types of malnutrition were not seen among the indigenous Americans under normal circumstances.
It was eventually discovered that the indigenous Americans learned long ago to add alkali — in the
form of ashes among North Americans and lime (calcium carbonate) among Mesoamericans — to corn meal to liberate the B-vitamin niacin, the lack of which was the underlying cause of the condition
known as pellagra.
This alkali process is known by its Nahuatl (Aztec)-derived name: nixtamalization.
Besides the lack of niacin, pellagra was also characterized by protein deficiency, a result of the inherent lack of two key amino acids in pre-modern maize, lysine and tryptophan. Nixtamalisation was also found to increase the lysine and tryptophan content of maize to some extent, but more importantly, the indigenous Americans had learned long ago to balance their consumption of maize with beans and other protein sources such as amaranth and chia, as well as meat and fish, in order to acquire the complete range of amino acids for normal protein synthesis.
Since maize had been introduced into the diet of non-indigenous Americans without the necessary cultural knowledge acquired over thousands of years in the Americas, the reliance on maize elsewhere was often tragic.
In the late 19th century pellagra reached endemic proportions in parts of the deep southern U.S., as medical researchers debated two theories for its origin:
the deficiency theory (eventually shown to be true) posited that pellagra was due to a deficiency of some nutrient, and
the germ theory posited that pellagra was caused by a germ transmitted by stable flies.
In 1914 the U.S. government officially endorsed the germ theory of pellagra, but rescinded this endorsement several years later as evidence grew against it.
By the mid-1920s the deficiency theory of pellagra was becoming scientific consensus, and the
theory was proved in 1932 when niacin deficiency was determined to be the cause of the illness.
Once alkali processing and dietary variety was understood and applied, pellagra disappeared. The development of high lysine maize and the promotion of a more balanced diet has also contributed to
its demise.
http://en.wikipedia.org/wiki/Maize