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 which 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. Pernicious anemia is a type of megaloblastic anemia caused by vitamin B12 deficiency, and it should be treated with vitamin B12. Patients with anemia should be evaluated by a physician in order to diagnose and address the underlying cause. 		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 have reported 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, or 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. The effects of vitamin B12 supplementation on the prevention or progression of Alzheimer's disease remain unclear. Well-designed clinical trials are needed before a conclusion can be made. 		C
Angioplasty
There are conflicting findings about the potential benefit or harm of taking folic acid plus vitamin B6 and vitamin B12 following angioplasty. Some evidence suggests that lowering homocysteine levels with prescription-strength folic acid and vitamins B12 and B6 for six months following coronary angioplasty reduced the risk of revascularization of target lesions and overall adverse cardiac events. Others have found this combination supplementation to increase restenosis (reoccurrence of narrowing of a blood vessel). Further research is needed before a conclusion can be made. 		C
Breast cancer
Researchers at Johns Hopkins University have reported that women with breast cancer tend to have lower vitamin B12 levels in their blood serum than do women without breast cancer. However, another study found no association between vitamin B12 levels and breast cancer risk. Supplementation with a combination of folic acid, vitamin B6, and vitamin B12 did not decrease the risk of breast cancer. Further research is needed before conclusions can be made. 		C
Cardiovascular disease/hyperhomocysteinemia
High homocysteine levels in the blood (hyperhomocysteinemia) has been suggested as being a risk factor for cardiovascular disease, blood clotting abnormalities, atherosclerosis, myocardial infarction (heart attack), and ischemic stroke. Taking vitamin B12 supplements in combination with other B vitamins (mainly folic acid) has been shown to be effective for lowering homocysteine levels. It is not clear whether lowering homocysteine levels results in reduced cardiovascular morbidity and mortality. More evidence is needed to fully explain the association of total homocysteine levels with vascular risk and the potential use of vitamin supplementation. 		C
Cervical cancer
Some evidence suggests that vitamin B12 supplementation may have a role in preventing cervical cancer. Further research is warranted in this area. 		C
Circadian rhythm sleep disorders
Taking vitamin B12 by mouth, in methylcobalamin form, does not seem to be effective for treating delayed sleep phase syndrome. Supplemental methylcobalamin with bright light therapy may be helpful for adolescents with circadian rhythm sleep disorders. More research is needed in this area. 		C
Cognitive function
Elevated serum homocysteine levels have been associated with lower neuropsychological test scores. However, there was a lack of association between low vitamin B12 blood levels and cognitive decline, Alzheimer's disease, or dementia; or between vitamin B12 concentrations and cognitive domains. There was conflicting evidence in regard to the relationship of serum folate and vitamin B12 status with cognitive impairment. More research is needed before a conclusion can be made. 		C
Depression
Higher blood levels of homocysteine are associated with increased depression in later life. However, a combination of folic acid, vitamin B12, and vitamin B6 was no better than placebo with respect to symptoms of depression in older men. Well-designed clinical trials are needed to confirm any potential benefit. 		C
Diabetic neuropathy
Some evidence suggests that supplementation with vitamin B12 may be helpful to diabetic neuropathy patients, primarily through symptomatic relief. Higher-quality studies are needed in the area. 		C
Fatigue
There is some evidence that intramuscular injections of vitamin B12 given twice per week may 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 conclusion can be made. 		C
Fractures (prevention)
Some evidence suggests that a combination of vitamins including vitamin B12 may help prevent fractures. Additional research is necessary. 		C
High cholesterol
Some evidence suggests that vitamin B12 in combination with fish oil may 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
Joint pain (elbow)
Preliminary research suggests that vitamin B12 may be effective for elbow pain, but evidence is lacking. Further research is needed. 		C
Shaky-leg syndrome
Clinical reports show that shaky-leg syndrome may be caused by disturbances in the cerebellum or related structures due to vitamin B12 deficiency. Further research is needed to confirm these results. 		C
Sickle cell disease
Early study suggests that a daily combination including folic acid, vitamin B12, and vitamin B6 may be a simple and relatively inexpensive way to reduce sickle cell disease patients' inherently high risk of endothelial damage. Further research is needed to confirm these results. 		C
Lung cancer
A clinical study found a correlation between vitamin B12 and folic acid supplementation and increased incidence of lung cancer in patients with heart disease in Norway, where folic acid fortification of foods is reportedly lacking. More high-quality research is needed with vitamin B12 alone to better understand this relationship. 		D
Stroke
In people with a history of stroke, neither high-dose nor low-dose vitamin B12 combinations containing pyridoxine, vitamin B12, and folic acid seem to affect risk of recurring stroke. 		D

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, chemotherapy side effects, chronic fatigue syndrome, diabetes, energy level enhancement, growth disorders (failure to thrive), hemorrhage, immunosuppression, improving concentration, inflammatory bowel disease, kidney disease, Leber's disease, liver disease, male infertility, malignant tumors, memory loss, mood (elevate), mouth and throat inflammation (atrophic glossitis), movement disorders (tremor), multiple sclerosis, myoclonic disorders (spinal myoclonus), neural tube defects, periodontal disease, poisoning (cyanide), prevention of pregnancy complications, protection from tobacco smoke, psychiatric disorders, seborrheic dermatitis, seizure disorders (West syndrome), tendonitis, thrombosis, thyrotoxicosis / thyroid storm (adjunct iodides), tinnitus, vitiligo.

Dosing Related terms
NS_patient-vitaminb12 Portions of this document last updated: Sept. 1, 2012

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

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