There are many causes for vitamin B12 deficiency.
Surprisingly, two of them are practices often undertaken to improve health:
1. Vegetarian diet
2. weight-loss surgery.
http://chriskresser.com/b12-deficiency-a-silent-epidemic-with-serious-consequences/
A primary sign of low B12 levels is a constant lack of energy.
Oct 26, 2015 - On Friday in Miami, Trump had ripped Carson for having even less energy than Jeb Bush, whom Trump has called low-energy.
“Ben Carson Doubts Donald Trump’s Temperament to be Commander In Chief”..........
And Carson, “Casper Choclate Milk Toast” does have the temperament? ReallY? I’m afraid that Carson would be sleeping at the switch when the need arises. He is a “nice guy” but not the leader this country so badly needs right now.