The human body needs vitamin B12 to make red blood cells, nerves, DNA, and carry out other functions. The average adult should get 2.4 micrograms a day. Like most vitamins, B12 can’t be made by the body . Instead, it must be gotten from food or supplements.

Symptoms of a shortage may include:

tiredness

lack of energy

pins and needs sensation

a sore and red tongue

muscle weakness

depression

problems with memory, understanding and judgement