Supplements: Vitamin B12 (Cobalamin)

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Vitamin B12 (Cobalamin)

Vitamin B12 is also called cobalamin. We need vitamin B12 in our daily diet to help the cells in our bodies grow and maintain normal function. It is an especially important vitamin for healthy bone marrow (where blood cells are formed) and the nervous system. Not getting enough vitamin B12 leads to a disease called pernicious anemia, which results in red blood cells not getting enough oxygen and causing disorders of the nervous system. The elderly are at higher risk for developing pernicious anemia because aging causes a decrease in the amount of vitamin B12 that the body is able to absorb from food.


The most important use of vitamin B12 is to improve the symptoms of pernicious anemia. These symptoms include weakness, pallor, and neurologic symptoms such as burning or prickling of the hands and feet, loss of balance, confusion, loss of memory, and moodiness.

Recent studies suggest a role for vitamin B12 in the prevention of heart disease. Patients taking a combination of folic acid, vitamin B12, and vitamin B6 lowered their blood levels of homocysteine, a substance that seems to be associated with a higher risk of heart disease.

Dietary Sources

Vitamin B12 is present in foods containing animal protein. The richest sources of it are liver and kidney. Other good sources of vitamin B12 include milk, eggs, fish, and cheese.

Other Forms

Vitamin B12 can be found in vitamin form as cyanocobalamin. It is available as tablets, softgels, or lozenges in multivitamin form (including children's chewable and liquid drops), B-complex form, or by itself.

How to Take It

  • To avoid disorders of vitamin B12 deficiency, adults should get 2.0 mcg of vitamin B12 daily.
  • People whose daily diet includes meat, milk, and other dairy products should be able to meet the 2.0 mcg recommended daily requirement without taking a vitamin supplement.
  • Vegetarians who do not eat animal protein products should take a vitamin supplement with water, preferably after eating.
  • Pregnant women should get 2.2 mcg of vitamin B12 daily and women who are breast-feeding should get 2.6 mcg of vitamin B12 daily. As with all medications and supplements, check with your health care provider before giving vitamin B12 supplements to a child.
  • Elderly people may need more than 2.0 mcg of vitamin B12 daily because of decreasing ability to absorb vitamin B12 from our diet as we age.
  • Elderly people should check with their health care provider to find out what dosage best fits their needs.


Vitamin B12 is non-toxic, but there is no known benefit to healthy individuals of taking more than the 2.0 mcg recommended daily allowance.

Possible Interactions

Vitamin B12 can have its absorption decreased by the drug metformin, which is used to treat hyperglycemia (high blood sugar). It also can be destroyed by megadoses (500 mg or greater) of vitamin C.

This document contains information relating to general principles of medical care that should not in any event be construed as specific instructions for individual patients. The reader is advised to check product information (including package inserts) for changes and new information regarding dosage, precautions, and contraindications before administering any drug. No claim or endorsements are made for any drug or compound currently in investigative use. No responsibility is assumed by the publisher for any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in any material herein.

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Dietary supplements are not intended to treat, cure, or prevent any disease or illness, and the information regarding these products has not been evaluated by the U.S. Food and Drug Administration.

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 Used by permission

Previously Published in OSA Today Reproduced by permission

Updated on: 03/10/16
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Vitamin B12
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Vitamin B12

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