Natural resources, quantification, microbial bioconversion, and bioactivities of vitamin B₁₂ for vegetarian diet

Vitamin B₁₂ is a water-soluble vitamin with a complex chemical structure. It can participate in the synthesis and repair of DNA in the human body and plays an important role in regulating the nervous system. The deficiency of vitamin B₁₂ will lead to megaloblastic anemia and neuropathy. Traditionally, animal foods have been the main dietary source of vitamin B₁₂. However, this review points to certain plant sources (such as algae, mushrooms, fermented vegetables, and fermented beans) as viable vitamin B₁₂ supplements for vegetarians. These sources validate our initial hypothesis that a plant-based diet can adequately provide essential nutrients previously thought to be available only through animal products. In terms of quantification, since the content of vitamin B₁₂ in food samples is low and is easily interfered by impurities, highly sensitive and specific analytical methods are used for the quantification of vitamin B₁₂. The findings from this review could be instrumental in developing fortified plant-based foods that could prevent B₁₂ deficiency in vegetarians and vegans, thereby broadening the scope of nutritional options available to those on plant-based diets.