B12 needs IF so it can be naturally absorbed. Given together (B12+IF) in a dietary supplement, the formulation supports the special dietary needs of people who can't produce adequate IF themselves.
Xeragenx has concluded its ingredient is Generally Recognized as Safe (GRAS) for other food uses, as determined by an independent panel of nationally recognized toxicologists and experts in food safety, following an evaluation of the safety of IF and related information, including production methods and purity criteria.
Many PNVs need a prescription because they contain 1mg of folic acid and may obscure underlying B12 deficiency and therefore require doctor supervision. Most PNV formulations contain B12 ...but without IF.
Adding IF to these formulations could allow lower B12 dosage to be given because of the high absorption through the body's receptor pathway.