Vitamin B12 is the largest of all vitamins and has a metal ion attached to it called cobalt. Different forms of B12 contain cobalamine. Only bacteria can make vitamin B12; therefore, vitamin B12 must come from the food you eat. It is naturally found in animal products, especially seafood. Vegetarians may need to supplement their diets with vitamin B12. Women between the ages of 19 and 50 need to consume 2.4 micrograms per day of vitamin B12 rich-foods.
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Bivalves with high vitamin B12 content include scallops, clams, oysters and mussels. Seafood bivalves have two shells with a body that resides between. Commonly, they are steamed open for eating. Steamed clams have the highest vitamin B12 content with about 84 micrograms per 3-ounce serving, while steamed mussels contain 20.4 micrograms. Eating six eastern raw oysters will give you 16.35 micrograms of vitamin B12, and B12 is abundant in scallops as well.
Caviar is the traditional name for the small black eggs of a wild sturgeon, a large fish living in coastal areas of oceans and rivers. Currently, caviar is used to describe the eggs of other fish as well, such as salmon caviar and whitefish caviar. Black caviar has 3.2 micrograms of vitamin B12 per tablespoon, while whitefish caviar contains 15.8 micrograms per ounce. All caviar is a good source of vitamin B12.
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The octopus is the most intelligent creature in the ocean without a skeleton, thus its classification is as an invertebrate. It comes in a variety of sizes and can range from 6 to 22 pounds. The common octopus is rich in vitamin B12 with 30.6 micrograms per 3 ounces. Octopus is used in a variety of foods; it is popular in Asian cuisine, as well as Greek classics.
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Aquatic hard-shelled crustaceans make up another group of vitamin B12-rich foods. Crustaceans, such as shrimp, crab and lobster, can be found throughout the world's oceans. These creatures provide protein, omega-3 fatty acids, minerals and vitamins, such as vitamin B12. Steamed shrimp contain 2.34 micrograms of vitamin B12 per three ounces, while steamed king crab is the highest at 9.77 micrograms. Other types of crab have high B12 content and steamed lobster contains 2.64 micrograms per 3 ounces.
Most ocean fish and some fresh-water fish can provide vitamin B12 to your diet. Not only rich in omega-3 fatty acids and minerals, fish provide, on average, 2 to 9 micrograms of vitamin B12 per 3-ounce serving. Cooked salmon has the highest levels of B12 for fish with 8.99 micrograms in half of a fillet, although canned sardines come second with 7.60 micrograms per 3 ounces. Wild rainbow trout has 5.4 micrograms of B12 per serving, while pollock and tuna contain less.
Based in Michigan, Keri Gardner has been writing scientific journal articles since 1998. Her articles have appeared in such journals as "Disability and Rehabilitation" and "Journal of Orthopaedic Research." She holds a Master of Science in comparative medicine and integrative biology from Michigan State University.