Dear MrsD, I already provided the 2003 link in post #25.
http://www.aafp.org/afp/2003/0301/p979.html
The 2011 link was provided to show the B12 deficiency treatment protocol that has changed markedly in the last 8 years.
http://www.aafp.org/afp/2011/0615/p1425.html
AND B12 also suffers greatly in people with a history of excessive alcohol consumption but this is often masked when taking an oral multi B and especially FOLATE ( ie., B9 or Folic Acid) replacement, as this will mask deficiency of B12, but the damage to peripheral nervous system continues.
QED.