Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the body through the urine.
The body can store vitamin B12 for years in the liver.
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. The vitamin is more available to the body from these cereals 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:
- Organ meats (beef liver)
- Shellfish (clams)
- Meat, poultry, eggs, milk and other dairy foods
- Some fortified breakfast cereals and nutritional yeasts
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 amount of B12. 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 vitamin that the body needs.
Deficiency occurs in people who:
- Are over the age of 50
- Follow vegetarian or vegan diet
- Have had stomach or intestinal surgery, such as weight loss surgery
- Have digestive conditions such as celiac disease or Crohn disease
Talk to your health care provider about taking Vitamin B12 supplements.
Low levels of B12 can cause:
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:
- Almost all multivitamins. Vitamin B12 is better absorbed by the body when it is taken along with other B vitamins, such as niacin, riboflavin, vitamin B6, and magnesium.
- A prescription form of vitamin B12 can be given by injection or as a nasal gel.
- Vitamin B12 is also available in a form that dissolves under the tongue (sublingual).
The Recommended Dietary Allowance (RDA) for vitamins reflects how much of each vitamin most people should receive on a daily basis. The RDA for vitamins may be used as goals for each person.
How much of each vitamin you need depends on your age and sex. Other factors, such as pregnancy and illnesses, are also important. Women who are pregnant or breastfeeding need higher amounts. Ask your provider which amount is best for you.
Dietary Reference Intakes for vitamin B12:
Infants (adequate intake)
- 0 to 6 months: 0.4 micrograms per day (mcg/day)
- 7 to 12 months: 0.5 mcg/day
- 1 to 3 years: 0.9 mcg/day
- 4 to 8 years: 1.2 mcg/day
- 9 to 13 years: 1.8 mcg/day
Adolescents and Adults
- Males and females age 14 and older: 2.4 mcg/day
- Pregnant teens and women: 2.6 mcg/day
- Breastfeeding teens and women: 2.8 mcg/day
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 218.
Salwen MJ. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 26.
Review Date 2/2/2019
Updated by: Emily Wax, RD, CNSC, University of Virginia Health System, Charlottesville, VA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.