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.
As I see it, the media recognizes that Carson COULD beat Hitlary. Trump was, and continues to be a threat to Hitlary as well. Now which one, or both, do they have to destroy to get their favorite (Hitlary) elected. The media thinks Trump will self-destroy but not Carson. Time will tell but you can rest assured, the media is going to continue to do their damdest to destroy ANY republican candidate. Today they are after Carson with a vengeance, its his turn in the barrel.