Is it ensure, insure, or assure?
"pellagra-preventing vitamin in enriched bread," 1942, coined from ni(cotinic) ac(id) + -in (2), chemical suffix; suggested by the American Medical Association as a more commercially viable name than nicotinic acid.
The new name was found to be necessary because some anti-tobacco groups warned against enriched bread because it would foster the cigarette habit. ["Cooperative Consumer," Feb. 28, 1942]
niacin ni·a·cin (nī'ə-sĭn)
A crystalline acid that is a component of the vitamin B complex and is used to treat and prevent pellagra. Also called nicotinic acid.
A water-soluble organic acid belonging to the vitamin B complex that is important in carbohydrate metabolism. It is a pyridine derivative and is a precursor of the coenzyme NAD. Niacin is found in liver, fish, and whole-grain foods. Deficiency of niacin in the diet causes pellagra. Also called nicotinic acid. Chemical formula: C6H5NO2.