Vitamin B12 is especially recognized among those following a vegan lifestyle, since it’s found primarily in animal-derived foods and typically requires supplementation. The form of B12 in MAXD, methylcobalamin, is the bioactive version of the vitamin and contributes to several important functions, particularly in maintaining immune health,¹ supporting the nervous system,⁴ and aiding energy production.² Common dietary sources of B12 include meat, fish, shellfish, eggs, and dairy.