Maybe, but the recognized sources of B12 in a normal diet are the animal products that people eat. http://funadvice.com/r/16b52v2g37j hence my reference to yeast extract dietary supplements for vegetarians. As far as I recall, vitamin B2 absorption rates deteriorate with age - particularly as you enter "middle age" and beyond. B12 absorption is also impaired by alcohol consumption, and elderly people often show unexpected signs of vitamin B12 deficiency http://funadvice.com/r/bvfitmp1cgo after alcoholic celebrations especially if they are not in the habit of maintaining a healthy balanced diet.
?? - vitamin B12 absorption