B12 deficiency has been observed among all forms of vegetarian diets and so supplementation is recommended. However, studies on the use of plant foods to increase the Cbl (B12) intake are promising, but still require more data. Some seaweed, mushrooms and fermented foods can be a useful source of Cbl, but the data are still insufficient and production is too heterogeneous. More trials with vegetarian people using supplements or fortified foods are needed to better explain the efficacy of different strategies of cobalamin (B12) uptake, focusing on the best dosages, media or foods, if reliable. 

Many foods such as non-dairy milks, cereals, spreads, and nutritional yeast flakes available in a plant based diet are naturally fortified with B12. Fortified vegan-friendly B12 is not bound to protein, therefore it has a greater bio-availability (increased and easier rate of absorption through the gut lining). This readily digestible form of B12 does not require your digestive system to work as vigorously, and therefore may help increase absorption rates dramatically where digestion may otherwise be compromised.