You can, but the foods richest in B12 are not the most commonly consumed foods. See below for the top 10 sources of B12. 1. Clams, oysters, and mussels 2. Liver: highest is lamb, then beef, veal, moose, turkey, duck, and goose 3. Caviar 4. Octopus 5. Fish: mackerel provides the most vitamin B-12, then herring, salmon, tuna, cod, sardines, trout, and bluefish 6. Crab and lobster 7. Beef, depends on the cut, lean fat-trimmed chuck has the most vitamin B12. 8. Lamb 9. Cheese: Swiss cheese provides the most, followed by mozzarella, Parmesan, and feta. 10. Eggs