This is the ADA position on B12; again, it's pretty much balanced and matter-of-fact-
Vitamin B-12
The vitamin B-12 status of some vegetarians
is less than adequate due to not regularly consuming reliable
sources of vitamin B-12 (12,46,47).
Lacto-ovo-vegetarians can obtain adequate
vitamin B-12 from dairy foods,
eggs, or other reliable vitamin B-12
sources (fortified foods and supplements),
if regularly consumed. For
vegans, vitamin B-12 must be obtained
from regular use of vitamin
B-12-fortified foods, such as fortified
soy and rice beverages, some breakfast
cereals and meat analogs, or Red
Star Vegetarian Support Formula nutritional
yeast; otherwise a daily vitamin
B-12 supplement is needed. No
unfortified plant food contains any
significant amount of active vitamin
B-12. Fermented soy products cannot
be considered a reliable source of active
B-12 (12,46).
Vegetarian diets are typically rich
in folacin, which may mask the hematological
symptoms of vitamin B-12
deficiency, so that vitamin B-12 deficiency
may go undetected until after
neurological signs and symptoms
may be manifest (47). Vitamin B-12
status is best determined by measuring
serum levels of homocysteine,
methylmalonic acid, or holotranscobalamin
II (48).
