B12 can be from animal sources, it is also made in the gi tract if you have
very healthful flora. So if you have b12 deficiency, it may be that you have
taken antibiotics or gotten these in some way. You want to be sure that at
least some of your food is living, so that it will have healthful bacteria on
it to go through to the GI tract. I am vegan, have not had any animal products
in about 7 years now, no sign of any B12 deficiencies, so it is not
necessarily caused by lack of flesh foods, as was previously thought and
taught

Dr. J G Knox BA, DC