Cobalamin; Cyanocobalamin
Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses what it needs of these vitamins, leftover amounts leave the body through the urine.
The body stores vitamin B12 in the liver. It can store a few years' worth of the needed amount.
Vitamin B12, like the other B vitamins, is important for protein metabolism. It helps in the formation of red blood cells and in the maintenance of the nervous system.
Vitamin B12 is naturally found in animal foods such as fish, meat, poultry, eggs, milk, and milk products. Vitamin B12 is generally not present in plant foods. Fortified breakfast cereals are a readily available source of vitamin B12. These cereals can be a good source of vitamin B12 for vegetarians. Some nutritional yeast products also contain vitamin B12.
You can get the recommended amounts of vitamin B12 by eating a variety of the foods including:
To find out if vitamin B12 has been added to a food product, check the nutrition fact panel on the food label.
The body absorbs vitamin B12 from animal sources much better than plant sources. Non-animal sources of vitamin B12 have different amounts of B12. With the exception of fortified foods, they are not thought to be good sources of the vitamin.
Vitamin B12 deficiency occurs when the body does not get or is not able to absorb the amount of the vitamin that the body needs.
Deficiency is most common in people who:
Talk to your health care provider about taking vitamin B12 supplements.
Low levels of B12 can cause:
Recommendations for vitamin B12, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:
Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.
Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.
Dietary reference intakes for vitamin B12:
Infants (AI)
Children (RDA)
Adolescents and Adults (RDA)
The best way to meet your body's vitamin B12 needs is to eat a wide variety of animal products.
Supplemental vitamin B12 can be found in the following:
Litwack G. Vitamins and nutrition. In: Litwack G, ed. Human Biochemistry. 2nd ed. Philadelphia, PA: Elsevier; 2022:chap 20.
Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 199.
Markell M, Siddiqi HA. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 27.
National Institutes of Health website. Vitamin B12: fact sheet for health professionals. ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/. Updated March 26, 2024. Accessed August 17, 2024.
BACK TO TOPReview Date: 1/19/2023
Reviewed By: Stefania Manetti, RD/N, CDCES, RYT200, My Vita Sana LLC - Nourish and heal through food, San Jose, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 08/19/2024.
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06/01/2025
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