Vitamin B12

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Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Megaloblastic anemia - due to vitamin B12 deficiency
Vitamin B12 deficiency is a cause of megaloblastic anemia. In this type of anemia, red blood cells are larger than normal and the ratio of nucleus size to cell cytoplasm is increased. There are other potential causes of megaloblastic anemia, including folate deficiency or various inborn metabolic disorders. If the cause is B12 deficiency, then treatment with B12 is the standard approach. Patients with anemia should be evaluated by a physician in order to diagnose and address the underlying cause. 		A
Pernicious anemia
Pernicious anemia (blood abnormality) is a form of anemia that occurs when there is an absence of intrinsic factor, a substance normally present in the stomach. Vitamin B12 binds with intrinsic factor before it is absorbed and used by the body. An absence of intrinsic factor prevents normal absorption of B12 and may result in pernicious anemia. Pernicious anemia treatment is usually lifelong; supplemental vitamin B12 given intramuscularly, intranasally, or by mouth. 		A
Vitamin B12 deficiency
Studies have shown that a deficiency of vitamin B12 can lead to abnormal neurologic and psychiatric symptoms. These symptoms may include: ataxia (shaky movements and unsteady gait), muscle weakness, spasticity, incontinence, hypotension (low blood pressure), vision problems, dementia, psychoses, and mood disturbances. Researchers report that these symptoms may occur when vitamin B12 levels are just slightly lower than normal and are considerably above the levels normally associated with anemia. People at risk for vitamin B12 deficiency include strict vegetarians, elderly people, breastfed infants, and people with increased vitamin B12 requirements associated with pregnancy, thyrotoxicosis, hemolytic anemia, hemorrhage, malignancy, liver or kidney disease. Administering vitamin B12 orally, intramuscularly, or intranasally is effective for preventing and treating dietary vitamin B12 deficiency. 		A
Alzheimer's disease
Some patients diagnosed with Alzheimer's disease have been found to have abnormally low vitamin B12 levels in their blood. However, vitamin B12 deficiency itself often causes disorientation and confusion and thus mimics some of the prominent symptoms of Alzheimer's disease. Well-designed clinical trials are needed before a strong recommendation can be made. 		C
Angioplasty
Some evidence suggests that folic acid plus vitamin B12 and pyridoxine daily can decrease the rate of restenosis in patients treated with balloon angioplasty. But this combination does not seem to be as effective for reducing restenosis in patients after coronary stenting. Due to the lack of evidence of benefit and potential for harm, this combination of vitamins should not be recommended for patients receiving coronary stents. 		C
Breast cancer
Researchers at Johns Hopkins University report that women with breast cancer tend to have lower vitamin B12 levels in their blood serum than do women without breast cancer. In a subsequent review of these findings, it was hypothesized that vitamin B12 deficiency may lead to breast cancer because it could result in less folate being available to ensure proper DNA replication and repair. Higher dietary folate intake is associated with a reduced risk of breast cancer. The risk may be further reduced in women who also consume high amounts of dietary vitamin B12 in combination with dietary pyridoxine (vitamin B6) and methionine. However, there is no evidence that dietary vitamin B12 alone reduces the risk of breast cancer. 		C
Cardiovascular disease/hyperhomocysteinemia
Hyperhomocysteinemia (high homocysteine levels in the blood) is a risk factor for coronary, cerebral, and peripheral atherosclerosis, recurrent thromboembolism, deep vein thrombosis, myocardial infarction (heart attack), and ischemic stroke. Elevated homocysteine levels may be a marker instead of a cause of vascular disease. However, it is not clear if lowering homocysteine levels results in reduced cardiovascular morbidity and mortality. Folic acid, pyridoxine (vitamin B6), and vitamin B12 supplementation can reduce total homocysteine levels; however, this reduction does not seem to help with secondary prevention of death or cardiovascular events such as stroke or myocardial infarction in people with prior stroke. More evidence is needed to fully explain the association of total homocysteine levels with vascular risk and the potential use of vitamin supplementation. 		C
Fatigue
There is some evidence that intramuscular injections of vitamin B12 given twice per week might improve the general well-being and happiness of patients complaining of tiredness or fatigue. However, fatigue has many potential causes. Well-designed clinical trials are needed before a recommendation can be made. 		C
High cholesterol
Some evidence suggests that vitamin B12 in combination with fish oil might be superior to fish oil alone when used daily to reduce total serum cholesterol and triglycerides. Well-designed clinical trials of vitamin B12 supplementation alone are needed before a conclusion can be drawn. 		C
Imerslund-Grasbeck disease
Administering vitamin B12 intramuscularly seems to be effective for treating familial selective vitamin B12 malabsorption (Imerslund-Grasbeck disease). Further research is needed to confirm these results. 		C
Shaky-leg syndrome
Preliminary clinical reports show that cyanocobalamin may help relieve tremor associated with shaky-leg syndrome. Further research is needed to confirm these results. 		C
Sickle cell disease
One study suggests that a practical daily combination may include folic acid, vitamin B12, and vitamin B6. This combination may be a simple and relatively inexpensive way to reduce these patients' inherently high risk of endothelial damage. Further research is needed to confirm these results. 		C
Circadian rhythm sleep disorders
Taking vitamin B12 orally, in methylcobalamin form, does not seem to be effective for treating delayed sleep phase syndrome. Supplemental methylcobalamin, with or without bright light therapy, does not seem to help people with primary circadian rhythm sleep disorders. 		D
Lung cancer
Preliminary evidence suggests that there is no relationship between vitamin B12 status and lung cancer. 		D
Stroke
In people with a history of stroke, neither high dose vitamin B12 combinations containing pyridoxine, vitamin B12, and folic acid nor low dose combinations containing pyridoxine, vitamin B12, and folic acid seem to affect risk of recurring stroke. 		D
Leber's disease
Vitamin B12 is contraindicated in early Leber's disease, which is a hereditary optic nerve atrophy. 		F

Key to grades
A Strong scientific evidence for this use
B Good scientific evidence for this use
C Unclear scientific evidence for this use
D Fair scientific evidence against this use (it may not work)
F Strong scientific evidence against this use (it likely does not work)

Grading rationale

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Aging, AIDS, allergies, amyotrophic lateral sclerosis, asthma, autism, chronic fatigue syndrome, cognitive function, depression, depressive disorder (major), diabetes, diabetic peripheral neuropathy, energy level enhancement, growth disorders (failure to thrive), hemorrhage, immunosuppression, improving concentration, inflammatory bowel disease, kidney disease, liver disease, male infertility, malignant tumors, memory loss, mood (elevate), mouth and throat inflammation (atrophic glossitis), multiple sclerosis, myoclonic disorders (spinal myoclonus), neural tube defects, osteoporosis, periodontal disease, poisoning (cyanide), protection from tobacco smoke, psychiatric disorders, seborrheic dermatitis, seizure disorders (West syndrome), tendonitis, thrombosis, thyrotoxicosis / thyroid storm (adjunct iodides), tinnitus, tremor, vitiligo.

Dosing Synonyms

NS_patient-vitaminb12

Portions of this document last updated:

Sept. 1, 2009

THIS EVIDENCE-BASED MONOGRAPH WAS PREPARED BY
THE NATURAL STANDARD RESEARCH COLLABORATION
(www.naturalstandard.com)


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