Vitamin B-12, also known as cobalamin, is the largest and most complex of all vitamins. Cobalamin is required in humans for the proper functioning of both blood cells and nervous tissue. Vitamin B-12 is synthesized only by microorganisms; it is not present in plants. Therefore it is generally not present in fruits, vegetables, legumes or grains. Common sources include meat, poultry and fish and, to a lesser degree, dairy.
Seafood
Seafood is an excellent source of vitamin B-12, providing more of this essential vitamin per serving than any other food. Of pescatarian sources, clams top the list. One 3-oz. serving of clams provides 84 micrograms of vitamin B-12. Other notable seafood sources include mussels, crab, salmon and rockfish. One 3-oz. serving of baked salmon exactly meets the recommended intake of 2.4 micrograms of vitamin B-12 per day for adults.
Meat
Meats such as pork and beef are other sources of vitamin B-12. One 3-oz. serving of cooked beef provides 2.1 micrograms of the vitamin, nearly meeting the daily recommendation. Cobalamin deficiency exists in 10 to 15 percent of persons over aged 60 and may manifest as anemia with neurological symptoms, including numbness and tingling of the legs, memory loss and dizziness. If you are a vegetarian, consider taking vitamin B-12 in pill form, or include fortified cereals in your diet.
Poultry
Chicken and turkey also contain significant amounts of vitamin B-12. One 3-oz. serving of chicken or turkey provides 0.3 micrograms of cobalamin, which is greater than 10 percent of the day's requirement. If you miss your daily dose of B-12, don't worry: significant amounts are stored in the body, and consequently clinical symptoms of B-12 deficiency do not arise unless you exclude the vitamin from your diet for years at a time.
Dairy
Rounding out the list of B-12 sources are dairy products, including milk and cheese. One 8-oz. glass of skim milk provides nearly a microgram of B-12, while 1 oz. of Brie cheese supplies 0.5 microgram. Yogurt also contains B-12; 1 cup of a popular commercial variety provides 10 percent of the day's requirement.
References
- "Biochemistry"; Pamela C. Champe; 2005
- Linus Pauling Institute at Oregon State University: Micronutrient Information Center
- LIVESTRONG MyPlate
