B12 Deficiency

Vitamin B12, known as the energy vitamin,
helps make DNA, blood and nerve cells.  It
is crucial for a healthy brain and immune
system.  Your metabolism wouldn't run
smoothly without it.

Where is it found?  Vitamin B12 is only
found in animal products like eggs, meat,
fish and dairy.  Many people do  not get
enough due to Celiac disease, being over 50,
or being a vegetarian.

Because the body can store B12 for 3-5 years,
early symptoms of a deficiency usually appear
gradually, so you are unlikely to notice them. 
Confirm any deficiency with a blood test.