for a discussion of research on B-12 levels in natural hygienists and
living-fooders, see:

http://www.beyondveg.com/billings-t/comp-anat/comp-anat-7b.shtml

The same research is also discussed in a long paper by Jack Norris
of Vegan Outreach at:

http://www.veganoutreach.org/health/b12.html

Tom Billings