Vitamin B-12, or Cobalamin, is the largest and most complex vitamin currently known to man.A slight deficiency of vitamin B-12 can lead to -
anemia,
fatigue,
mania, and
depression,
while a long term deficiency can cause permanent damage to the brain and central nervous system. Vitamin B12 can only be manufactured by bacteria and can only be found naturally in animal products, however, synthetic forms are widely available.
Vitamin B12 can be consumed in large doses because excess is excreted by the body or stored in the liver for use when supplies are scarce. Stores of B12 can last for up to a year.
SOURCE OF VIT. B12~
Vitamin B12 is the one vitamin that is available only from fish, poultry, meat or dairy sources in food.
Cheese ,Cows Milk ,Eggs ,fish ,oysters,Cod, beef, yoghurt, chicken,lamb (mutton), liver (lamb, beef) ....