The Carson/SDA food pyramid. 
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.
