What is Doctor’s Best Fully Active B12?Doctor’s Best Fully Active B12 supports healthy memory, mood, circulation and well-being. It provides methylcobalamin, the most biochemically active form of vitamin B12. Vitamin B12 is essential for humans at every stage of life, from conception through advanced age. Healthy vitamin B12 status is linked to healthy mood and memory management. This vitamin is required for such fundamental life processes as gene regulation (epigenetics), nerve cell communication, and the management of homocysteine, which may cause endothelial cell damage.How does it work?Vitamin B12 is the most chemically complex of all the vitamins. Methylcobalamin is the most active form of vitamin B12. Methylcobalamin is a large molecule with an intricate cage-like structure that encloses a single cobalt atom. Methylcobalamin is used in specific biochemical functions.