" 

 == Inaccurate or inadequate citations re absorption == 

 ""absorption of vitamin B12 actually begins in the mouth"" 
 There is anecdotal evidence that this is true, but there is no confirmation of it in the citation (9) http://www.nal.usda.gov/fnic/DRI//DRI_Thiamin/306-356_150.pdf.  Citation required. 

 ""high oral doses of free crystalline B12 is absorbed along the entire intestine by passive diffusion"" 
 If that is true, what is the reference?  I have only seen references to absorption (passive or otherwise) via the ileum. 

 ""Sublingual methods of replacement are effective only because of the typically high doses (0.5 mg) which are swallowed"" 
 This statement is too strong, and tends to contradict the earlier statement that absorption begins in the mouth.  It should be preceded by (say) ""It may be that""."