Vitamin B12 is also called cobalamin, the nature of vitamin B12 are the microbial synthesis of higher plants and animals can not manufacture vitamin B12. Vitamin B12 need a gut secretions (endogenous factors) to help a vitamin can be absorbed only. The main physiological function of vitamin B12 is involved in the manufacture of bone marrow red blood cells, to prevent pernicious anemia; to prevent damage to the brain.