Vitamin B 12 , an essential nutrient, is also known as cobalamin. The cobal in the name refers to the metal cobalt contained in B 12 . Vitamin B 12 is required for the normal activity of nerve cells and works with folate and vitamin B 6 to lower blood levels of homocysteine , a chemical in the blood that might contribute to heart disease. B 12 also plays a role in the body's manufacture of S-adenosylmethionine (SAMe) .
Anemia is usually (but not always) the first sign of B 12 deficiency. Earlier in this century, doctors coined the name "pernicious anemia" for a stubborn form of anemia that did not improve even when the patient was given iron supplements. Today we know that pernicious anemia comes about when the stomach fails to excrete a special substance called intrinsic factor. The body needs the intrinsic factor for efficient absorption of vitamin B 12 . In 1948, vitamin B 12 was identified as the cure for pernicious anemia. B 12 deficiency also causes nerve damage, and this may, in some cases, occur without anemia first developing.
Vitamin B 12 has also been proposed as a treatment for numerous other conditions, but as yet there is no definitive evidence that it is effective for any purpose other than correcting deficiency.
Extraordinarily small amounts of vitamin B 12 suffice for daily nutritional needs. The official US and Canadian recommendations for daily intake are as follows:
- 0-6 months: 0.4 mcg
- 7-12 months: 0.5 mcg
- 1-3 years: 0.9 mcg
- 4-8 years: 1.2 mcg
- 9-13 years: 1.8 mcg
Males and Females
- 14 years and older: 2.4 mcg
- 2.6 mcg
- 2.8 mcg
Vitamin B 12 is available in three forms: cyanocobalamin, hydrocobalamin, and methylcobalamin. The first is the most widely available and least expensive, but some experts think that the other two forms are preferable.
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For correcting absorption problems caused by medications, taking vitamin B 12 at the level of dietary requirements should suffice.
For other purposes, enormously higher daily doses—ranging from 100 to 2,000 mcg—are sometimes recommended.
Vitamin B 12 is also sometimes recommended for numerous other problems, including asthma , osteoporosis , periodontal disease , and depression . But, there is not a lot of evidence as yet that it really works.
Interactions You Should Know About
If you are taking:
Colchicine , AZT , medications that reduce stomach acid (such as the H2 blocker ranitidine [Zantac] or the proton pump inhibitor omeprazole [Prilosec], oral hypoglycemics (such as metformin or phenformin), slow-release potassium supplements, or if you are exposed to nitrous oxide anesthesia: You may need extra B 12 . Another option is to take extra calcium , which may, in turn, improve B 12 absorption.
- Reviewer: EBSCO CAM Review Board
- Review Date: 09/2012 -
- Update Date: 09/10/2012 -