Fermented food are a great source of Vitamin B 12, especially for vegetarians. Those eating meat get Vitamin B12 from the meat. It's actually the bacteria that start lacto fermenting the flesh as soon as the animal is killed and cut for the meat.
The same Vitamin B12 can come to a vegetarian diet through these fermented food. The fermented food are good source of Vitamin B family and they help the good bacteria get nurtured in our system and support a good gut health.