Summarize:

Fish such as trout, salmon, tuna, and haddock all contain high levels of vitamin B12. Clams are also naturally high in vitamin B12. As well, beef products, including beef liver, are high in vitamin B12. Try to add more fish and beef to your diet by having at least one serving a day. Dairy products like yogurt and cheese, as well as eggs, are also high food sources of vitamin B12. Whole wheat cereal is also known to have high levels of vitamin B12. Add whole wheat cereal to your diet by having one bowl a day for breakfast with fruit.
Consume more fish and beef. Have more yogurt, cheese, and eggs.