Vitamin B12 - Sources

Food sources

Only bacteria can synthesize vitamin B₁₂. Vitamin B₁₂ is present in animal products such as meat, poultry, fish (including shellfish), and to a lesser extent milk, but it is not generally present in plant products or yeast. Fresh pasteurized milk contains 0.9 mcg per cup and is an important source of vitamin B₁₂ for some vegetarians. Those vegetarians who eat no animal products need supplemental vitamin B₁₂ to meet their requirements. Also, individuals over the age of 50 should obtain their vitamin B₁₂ in supplements or fortified foods like fortified cereal because of the increased likelihood of food-bound vitamin B₁₂ malabsorption.

Most people do not have a problem obtaining the RDA of 2.4 mcg/day of vitamin B₁₂ in food. In the United States, the average intake of vitamin B₁₂ is about 4.5 mcg/day for young adult men, and 3 mcg/day for young adult women. In a sample of adults over the age of 60, men were found to have an average dietary intake of 3.4 mcg/day and women 2.6 mcg/day. Some foods with substantial amounts of vitamin B₁₂ are listed in the table below along with their vitamin B₁₂ content in micrograms (mcg). For more information on the nutrient content of foods you eat frequently, search the USDA food composition database.

Food	Serving	Vitamin B₁₂ (mcg)
Clams (steamed)	3 ounces	84.0
Mussels (steamed)	3 ounces	20.4
Crab (steamed)	3 ounces	8.8
Salmon (baked)	3 ounces*	2.4
Rockfish (baked)	3 ounces	1.0
Beef (cooked)	3 ounces	2.1
Chicken (roasted)	3 ounces	0.3
Turkey (roasted)	3 ounces	0.3
Egg (poached)	1 large	0.4
Milk	8 ounces	0.9
Brie (cheese)	1 ounce	0.5

*A three-ounce serving of meat or fish is about the size of a deck of cards.

Supplements

Cyanocobalamin is the principal form of vitamin B₁₂ used in supplements but methylcobalamin is also available. Cyanocobalalmin is available by prescription in an injectable form and as a nasal gel for the treatment of pernicious anemia. Over the counter preparations containing cyanocobalamin include multivitamin, vitamin B-complex, and vitamin B₁₂ supplements.

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