Vitamin B12 Status and Supplementation in Plant-Based Diets

Plant-based diets are increasingly popular worldwide. A well-planned plant-based diet lowers the risk of cardiovascular disease, type 2 diabetes and certain cancers. In contrast, a poorly planned plant-based diet increases the risk of certain micronutrient deficiencies, chiefly, vitamin B-12 (B-12). Because B-12 is not present in plants or in unfortified plant-based foodstuffs, the safest way to prevent its deficiency in plant-based diets is to take an oral B-12 supplement. Studies determining the dose and frequency of B-12 to be taken by healthy individuals on a plant-based diet to support an adequate B-12 status are scarce. Here, we summarize the natural sources, metabolic requirements, biomarker findings with and without supplementation with B-12, and current recommendations to help prevent vitamin B-12 deficiency in healthy individuals adhering or transitioning to plant-based diets. This review focuses on the prevention of vitamin B-12 deficiency in healthy individuals adhering to plant-based diets. The information covered in this review does not apply to individuals suffering from autoimmune-based malabsorption of vitamin B-12 resulting from pernicious anemia due to atrophic gastritis, other acquired causes of B-12 malabsorption or to those with genetic disorders that impair vitamin B-12 absorption, transport and utilization.