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 B12 (B12). Because B12 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 B12 supplement. Studies determining the dose and frequency of B12 to be taken by healthy individuals on a plant-based diet to support an adequate B12 status are scarce. Here, we summarize the natural sources, metabolic requirements, biomarker findings with and without supplementation with B12, and current recommendations to help prevent vitamin B12 deficiency in healthy individuals adhering or transitioning to plant-based diets. This review focuses on the prevention of vitamin B12 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 B12 resulting from pernicious anemia due to atrophic gastritis, other acquired causes of B12 malabsorption or to those with genetic disorders that impair vitamin B12 absorption, transport and utilization.
Keywords: homocysteine; malnutrition; methylmalonic acid; micronutrient deficiency; plant-based diet; vitamin B12.
Plain language titleVitamin B12 in Plant-Based DietsPlain language summaryPlant-based diets are increasingly popular worldwide. Because vitamin B12 is not found in plants, individuals must acquire the micronutrient by consuming fortified foods or by taking an oral vitamin B12 supplement. We review B12 sources, required daily intake, and use of B12 supplements among those on plant-based diets. The safest way to prevent B12 deficiency in individuals adhering to plant-based diets is by using an oral B12 supplement.