Vitamin B12, whether in supplements, fortified foods, or animal products, comes from micro-organisms. ↑ Rizzo G, Laganà AS, Rapisarda AM, La Ferrera GM, Buscema M, Rossetti P, Nigro A, Muscia V, Valenti G, Sapia F, Sarpietro G, Zigarelli M, Vitale SG (2016). "Vitamin B12 among Vegetarians: Status, Assessment and Supplementation".