Vitamin B12  Vitamin B12 is essential to building and
maintaining a healthy brain. You need B12 to make myelin, which
insulates the axons (think nerve cell “threads”) of brain cells.
You also need B12 to make neurotransmitters (hormones) that are
key to mood and memory. It also is vital for proper cellular
metabolism, DNA synthesis, and the regulation of fatty acids.
B12 is a key “methylator,” and reduces homocystiene, high levels
of which are associated with depression and heart disease. This
is the big kahuna of vitamins, one of the largest molecules we
absorb. Have a look at that 3d model!  The only thing on the
planet that makes B12 are bacteria, which happen to grow in the
stomachs of animals such as cows, goats, fish and shellfish
primary sources. B12 is one of the best arguments for the
consumption of some meat and animal products. Strict vegans must
take B12 in supplement or risk irreversible nerve damage.
Parietal (wall) cells in the human stomach make a special
protein called intrinsic factor needs