How do i know how much vitamin b12 can you take a day ?

Daily requirement 3.: Daily requirement of vit B12 for us population is 3.4 mcg at your age and you are probabely getting that in your diet at your age.It is required for red cell formation and neurological functions and its deficiency can cause anemia and neurological problems.It is found in poultry, eggs, milk&milk and fortified breakfast serials.Older people&those on acid suppression meds need supplement 1000 mcg dail.