Although we can only speculate about why these complexes developed, they may have been acquired by immunization against the extraordinarily high vitamin [B.sub.12] concentrations (15 mg/week for several months), with subsequent appearance of
antivitamin [B.sub.12] antibodies.
There are several antagonists of the synthesis, metabolism, or actions of vitamins, where competitive biochemical activity occurs because of the resemblance of an "
antivitamin" to the active vitamin molecule.
Several researchers have used different thermal treatments to improve the nutritional quality of crude soybean by making milder the antinutritional factors (ANF), which include inhibitors of trypsin, hemagglutinins, goitrogenic substances,
antivitamins, isoflavone and phytates (Pedrosa et al., 2012; Torrezan, Frazier & Cristianini, 2010).