Some of the top food sources for vitamin B12, per 28 grams or roughly 1 ounce (daily need is 6 micrograms):
clams: 27.6 micrograms
liver: 23.9 micrograms
fortified cereal: 5.8 micrograms
mackerel: 5.3 micrograms
king crab: 3.2 micrograms
beef steak: 2.1 micrograms
swiss cheese: 0.8 micrograms
fortified tofu: 0.6 micrograms
eggs: 0.3 micrograms
low fat yogurt: 0.1 micrograms
More here.
