Nixtamalization and the maize that crossed without it
Mesoamerica did not merely domesticate maize; it invented the alkaline cooking that makes maize a safe staple, releasing bound niacin and tryptophan, multiplying its calcium and destroying most of its fungal toxins. The grain crossed the Atlantic in Spanish ships. The chemistry did not. Pellagra was first recognised as a clinical problem in eighteenth-century Spain and Italy, and the deficiency behind it was not identified until the 1920s and 1930s.
Why this wins its question: The line "Europe took maize and got pellagra" circulates widely with nothing under it: no chemistry, no numbers, no date, and usually a moral attached at either end. This object binds each part of the chain to a peer-reviewed source that was opened and read — the antiquity of the technique, the quantified effect of lime on calcium, aflatoxin and fumonisin, the unsettled question of whether niacin or amino-acid balance does the work, the clinical first recognition of pellagra in Spain and Italy rather than in the colonies, and the four-century lag before the deficiency was named. It also separates, explicitly, the well-evidenced failure of transmission from the unevidenced charge of deliberate suppression, and grades its confidence accordingly.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
Nixtamalization is the alkaline cooking of maize, and it is old: the review of Latin American indigenous biotechnology by Villanueva-Flores and Garcia-Atutxa dates the evidence to "~1200-1500 BC in Guatemala" and describes it as an "ancient Mesoamerican alkaline cooking of maize" — a food technology, not a recipe, transmitted socially over three millennia.
What the lime does is chemistry with a clinical result. The same review states that treatment with calcium hydroxide liberates "niacin and tryptophan, preventing pellagra and niacin deficiency", and that it "significantly increases maize's calcium content and reduces harmful mycotoxins". A population living on nixtamalized maize is eating a materially different food from one living on the same grain untreated.
The magnitudes are measurable and have been measured. In the food science review by Kamau, Nkhata and Ayua, nixtamalization is "boiling the corn in water containing lime (calcium hydroxide) at a concentration range of 1%-5%" followed by overnight steeping, washing and grinding; calcium "increased by 94% during nixtamalization of maize", with reported increases "up to 400%"; aflatoxin was "reduced by 80%-100%" under lime cooking, and fumonisin fell to "retention of only 18% of the initial concentration", some 75% being washed away. Protein rose only slightly, "from 8% to 9%".
The mechanism is not fully settled, and the disagreement is worth keeping on the record rather than smoothing over. The food science review reports that "lime treatment of maize improves balance of essential amino acids" and cites research indicating that "the difference in amino acid balance rather than in bound niacin was responsible for the difference between raw and lime processed maize" — a different emphasis from the bound-niacin explanation usually given in summary accounts, including the one in the ethnobiological review cited here.
The transfer carried the plant and left the process behind. The ethnobiological review states flatly that "maize was adopted without the corresponding Indigenous processing knowledge", causing "preventable disease" — the single most consequential omission in the whole Columbian exchange of foodstuffs, and one that no sixteenth-century agronomy was equipped to notice, since the nutrient at stake would not be identified for another four hundred years.
The cost landed first on the poor of the two countries that had done most to spread the plant. The review of NAD deficiency by Feuz, Meyer-Ficca and Meyer records that "pellagra was first recognized as a clinical problem during the 18th Century in Spain and Italy, when epidemics of sun-induced skin lesions occurred among people working outdoors". Spain exported the grain and then met the disease at home, in its own fields, before anywhere else.
The explanation took two centuries more. The same review credits Joseph Goldberger and Conrad Elvehjem with pinpointing "the lack of bioavailable dietary niacin in the corn-based diets of affected patients as the cause for pellagra", after outbreaks that "began to occur in the southern United States" in the late nineteenth century. The Mesoamerican technique had been solving the problem for three thousand years before the vitamin behind it had a name.
Whether the omission was ignorance or suppression is contested, and is reported here as one reading rather than as fact. The ethnobiological review asserts that Spanish colonizers "misunderstood or deliberately suppressed such knowledge" rather than recording it. That is a strong charge carried by a paper whose declared purpose is vindication — its title is "From forgotten to frontier: vindicating Latin America's indigenous biotechnology" — and it is not accompanied there by documentary citation for the deliberate half of the alternative. The failure of transmission is well evidenced; the intent behind it is not.
Nixtamalization is one item in a longer inventory the same review assembles, which is the reason to treat it as technology rather than custom: cassava fermentation (masato, parakari), pulque from agave, pozol from fermented maize, tocosh from fermented potatoes, chuno by freeze-drying, cochineal dye production, barbasco (wild yam, later the raw material of steroid synthesis), cacao fermentation, and the engineered Amazonian dark earths (terra preta).