B12 deficiency is common and reported to affect 25% of the U.S. population.  It strikes up to 15% (5.9 million) older adults > age 64.  The CDC reports, one out of every 31 Americans > age 50 are B12 deficient.  This report underestimates the incidence by using a cut-off range far too low.  The incidence in infants and children is unknown, which is problematic.