I know, it was a while ago when I proposed you this riddle. Did you figure it out? ;)
Pellagra was a widely diffused diseases at the beginning of 1900, associated to a diet mostly based on corn. It took many years to understand that pellagra was caused by a deficiency of vitamin B3. Curiously, people from Mesoamerica, where maize has been a staple food for centuries, never developed pellagra.
Maize actually contains vitamin B3, but in a “bound” form that is hard to absorb for the human body (funny on the other hand, how the “eme” iron, the iron form bound to the huge hemoglobin molecules, is absorbed more easily than the free form! It’s interesting how our body works :)). Mexicans, as well as the other Mesoamericans, prepare maize flour differently from the Europeans. Instead of grinding the corn tout court, they treat it first with an alkaline solution that generally consists of lime water. This process is called Nixtamalization and allows to free vitamin B3 from its bound form, promoting its absorption.
Probably, Mesoamericans have implemented this process to obtain a higher quality flour: fine, with better flavour and kneadable, so that it can be employed to prepare tacos or other recipes. Anyway, this has saved them from the terrible spread of pellagra that has lashed both Europe and Unites States.
Who knows if history would have been any different if the Nixtamalization process would have been imported along with corn from the New World!
The original solution can be found here.