Vitamin B12 is an essential micronutrient for hematological and neurological health, yet deficiency remains common worldwide despite the widespread capacity of microorganisms to synthesize cobalamin. This apparent paradox arises from fundamental constraints imposed by human physiology, which restrict vitamin B12 absorption to intrinsic factor dependent uptake in the terminal ileum, rendering endogenous microbial synthesis within the gut nutritionally inaccessible. Presenting the background of vitamin B12 biology and absorption, this review focuses on this biological paradox and its emerging solutions. Evidence from fermented foods, cereals, and engineered microbial processes demonstrates that B12 can be incorporated into foods in bioavailable forms. Overall, the work supports microbiome-informed, food-based strategies aligned with human physiology to effectively address global B12 deficiency.
Jayaprakasan et al. (Tue,) studied this question.