[ppseafield]

You used to be able to acquire B12 from crops because some of the natural bacteria flora contained the cyanobacteria that make it. Modern farming's use of industrial pesticides means we can't use that as a source anymore.

The Jain's diet is largely plant-based. It allows for dairy, but only in the case that the cows aren't hurt as part of the process.

http://www.jainfoodie.com/jain-food-restrictions/