What is it?
Vitamin B12 is an essential vitamin. This means that the body requires vitamin B12 to work properly. Vitamin B12 can be found in foods such as meat, fish, and dairy products. It can also be made in a laboratory. It is often taken in combination with other B vitamins.
Vitamin B12 is most commonly used for vitamin B12 deficiency, a condition in which vitamin B12 levels in the blood are too low, as well as cyanide poisoning and high levels of homocysteine in the blood (hyperhomocysteinemia).
Effective for …
- A rare inherited condition marked by vitamin B12 deficiency (Imerslund-Grasbeck disease). Injecting vitamin B12 as a shot for 10 days followed by monthly injections for the remainder of life is effective for treating people with an inherited disease that results in poor absorption of vitamin B12.
- Vitamin B12 deficiency. Vitamin B12 can treat and prevent vitamin B12 deficiency. It can be taken by mouth, as a shot, or through the nose. The shot works best in people with severe vitamin B12 deficiency.
Probably Effective for …
- Cyanide poisoning. Administering hydroxocobalamin (Cyanokit), a natural form of vitamin B12, as a shot for a total dose of up to 10 grams is likely an effective treatment for cyanide poisoning. Treatment of cyanide poising with hydroxocobalamin (Cyanokit) has been approved by the U.S. Food and Drug Administration (FDA).
- High levels of homocysteine in the blood (hyperhomocysteinemia). Taking vitamin B12 by mouth, along with folic acid and sometimes pyridoxine (vitamin B6), can lower blood levels of homocysteine.
Possibly Effective for …
- An eye disease that leads to vision loss in older adults (age-related macular degeneration or AMD). Some research shows that taking vitamin B12 with other B vitamins, including folic acid and vitamin B6, might help prevent an eye disease called age-related macular degeneration. But the effects of vitamin B12 alone on AMD are not clear.
- Canker sores. Using an ointment containing vitamin B12 helps to reduce pain of canker sores. Also, early research shows that taking vitamin B12 1000 mcg under the tongue (sublingually) might help to reduce the number of canker sore outbreaks, the duration of outbreaks, and pain caused by the canker sores.
- Nerve pain caused by shingles (postherpetic neuralgia). Some research shows that injecting vitamin B12 in the form of methylcobalamin under the skin six times weekly for up to 4 weeks reduces pain more than taking vitamin B12 by mouth or injecting lidocaine under the skin in people with nerve damage from shingles. Other research shows that it reduces pain and the need for painkillers. Adding thiamine or lidocaine to the treatment also seems to reduce itching.
Possibly Ineffective for …
- Cancer. Research suggests that taking vitamin B12 in the form of cyanocobalamin along with folate and vitamin B6, with or without eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) does not reduce the risk of developing cancer in older adults with heart disease. Some research actually suggests that taking vitamin B12 and folic acid daily for 2 years might increase the risk of cancer in older people.
- Cataracts. Taking vitamin B12 along with vitamin B6 and folic acid doesn’t seem to prevent cataracts in women. In fact, it might even increase the risk of having the cataracts removed in some women.
- Disorders that affect when a person sleeps and when they are awake. Taking vitamin B12 by mouth does not seem to help people with sleep disorders.
- Memory and thinking skills (cognitive function). Taking vitamin B12, alone or with folic acid and vitamin B6, doesn’t seem to improve memory, language, or the ability to organize and plan in elderly people.
- Fall prevention. Taking folic acid with vitamin B12 doesn’t seem to prevent falls in older people taking vitamin D.
- Fractures. Taking vitamin B12 and folic acid, with or without vitamin B6 daily for 2-3 years does not seem to reduce the risk of fractures in older people with osteoporosis.
- Physical performance in elderly adults. Taking folic acid with vitamin B12 doesn’t seem to help older people who are already taking vitamin D walk better or have stronger hands.
- Stroke. Research suggests that people who consume more vitamin B12 in their diet or those who take vitamin B12 supplements do not have a reduced risk of stroke or stroke reoccurrence.
Insufficient Evidence to Make a Determination for …
- Alzheimer disease. Some early research suggests that higher vitamin B12 intake does not prevent Alzheimer disease. However, other early research shows that taking vitamin B12 along with vitamin B6 and folic acid for 2 years might slow brain changes that are linked with mental decline and Alzheimer disease.
- A procedure to open a blocked or narrowed blood vessel (angioplasty). Research is inconsistent about the benefits of taking folic acid plus vitamin B6 and vitamin B12 following angioplasty. Some research suggests that it might decrease the risk of re-blockage of the blood vessels after balloon angioplasty. However, it does not seem to benefit people who had a tube (coronary stent) placed in the arteries.
- Hardening of the arteries (atherosclerosis). Early research shows that taking vitamin B12, aged garlic extract, folic acid, vitamin B6, and L-arginine daily for 12 months slows the progression of clogged arteries and improves blood vessel function in people at risk for clogged arteries. The effect of vitamin B12 alone is not clear.
- Eczema (atopic dermatitis). Early research shows that applying a vitamin B12 cream (Regividerm) to the affected area twice daily helps treat eczema.
- Breast cancer. There is no evidence that dietary vitamin B12 alone reduces the risk of breast cancer. However, vitamin B12 may reduce the risk of breast cancer when taken with folate, vitamin B6, and methionine.
- Cancer of the cervix. Early research suggests that different forms of vitamin B12 taken together with a thiamine derivative (benfotiamine) and vitamin B6 might improve some symptoms of nerve pain associated with diabetes.
- Nerve damage in the hands and feet caused by cancer drug treatment. Early research shows that taking B vitamins that include vitamin B12 along with cancer drugs doesn’t prevent nerve pain caused by cancer drugs.
- A lung disease that makes it harder to breathe (chronic obstructive pulmonary disease or COPD). Taking vitamin B12 might improve endurance in people with COPD.
- Colon cancer, rectal cancer. Some population research suggests that people who consume more vitamin B12 in their diet have a lower risk of developing colon or rectal cancer. But early research shows that taking vitamin B12 with folic acid and vitamin B6 daily for up to 7.3 years does not reduce the risk of developing colorectal cancer in women.
- Diseases, such as Alzheimer disease, that interfere with thinking (dementia). Early research in people with Parkinson disease suggests that higher blood levels of vitamin B12 are linked to a lower risk of getting dementia. But it isn’t known if taking vitamin B12 supplements reduces the risk of dementia.
- Depression. Eating more food that contains vitamin B12 has been linked with a lower risk of depression in older men. Lower vitamin B12 levels in the blood of pregnant women has been linked with an increased risk for depression. But it’s unclear if eating more vitamin B12 or taking supplements can reduce the risk for depression in pregnant women.
- Nerve pain in people with diabetes (diabetic neuropathy). Early research suggests that different forms of vitamin B12 taken together with a thiamine derivative (benfotiamine) and vitamin B6 might improve some symptoms of nerve damage associated with diabetes. Taking a specific medical food containing specific forms of vitamin B12, folic acid, and vitamin B6 also seems to have beneficial effects. Taking vitamin B12 alone by mouth or injected into the vein might help reduce pain but does not improve motor or sensory nerve function in people with nerve damage caused by diabetes.
- Diarrhea. Early research suggests that taking twice the recommended daily allowance of vitamin B12, with or without folic acid, does not reduce the risk of diarrhea in children.
- Fatigue. There is some evidence that receiving shots containing 5 mg of vitamin B12 in the form of hydroxocobalamin twice weekly might improve general well-being and happiness in people with fatigue.
- Swelling (inflammation) of the liver caused by the hepatitis C virus (hepatitis C). Early research shows that giving an injection of vitamin B12 in the form of cyanocobalamin every 4 weeks along with standard care can improve hepatitis C treatment.
- High levels of fats called triglycerides in the blood (hypertriglyceridemia). Some research suggests that taking 7.5 mcg of vitamin B12 together with 5 grams of fish oil might be more effective then fish oil alone when used daily to reduce total cholesterol and triglyceride levels.
- Infant development. Taking vitamin B12 during pregnancy doesn’t seem to help improve cognitive function or brain development in infants.
- Infection of the airways. Early research shows that taking twice the recommended daily allowance of vitamin B12, with or without folic acid, does not reduce the risk for infections of the lower airways in children.
- Lung cancer. Some research suggests that higher levels of vitamin B12 in the blood might be linked with an increased risk for lung cancer. But not all research agrees.
- Pancreatic cancer. Men who are smokers who get more vitamin B12 from pills or as part of the diet don’t seem to have a lower risk of pancreatic cancer. It’s unclear if women or people who don’t smoke might benefit from taking more vitamin B12.
- Nerve damage in the hands and feet (peripheral neuropathy). Early research shows that taking a specific product containing vitamin B12 (Keltican) daily for 60 days reduces pain by 44% and reduces the need for painkillers by over 75% in people with nerve damage in parts of the body such as the hands and feed.
- Psoriasis. Early research shows that a specific cream containing vitamin B12 and avocado oil (Regividerm, Regeneratio Pharma AG) reduces symptoms of psoriasis as effectively as standard care and causes less irritation.
- Schizophrenia. Early research shows that taking vitamin B12 with folic acid daily for 16 weeks can improve symptoms of schizophrenia related to abnormal emotions and behavior. But the treatment only seems to benefit some patients.
- Ringing in the ears (tinnitus). Early research shows receiving vitamin B12 shots might help improve ringing in the ears in people with low levels of vitamin B12. But it doesn’t seem to help people who have normal levels of vitamin B12.
- Blood clots that form in the veins (venous thromboembolism or VTE). Population research suggests that having low levels of vitamin B12 might be linked to an increased risk for blood clots in the veins. But research evaluating the use of vitamin B12 to prevent blood clots in the veins is unclear.
- Chronic fatigue syndrome (CFS).
- Heart disease.
- Immune system problems.
- Lyme disease.
- Memory problems.
- Multiple sclerosis.
- Other conditions.
More evidence is needed to rate the effectiveness of vitamin B12 for these uses.
When applied to the skin: Vitamin B12 is LIKELY SAFE for most people when used appropriately.
When sprayed into the nose: Vitamin B12 is LIKELY SAFE for most people. Vitamin B12 is considered safe, even in large doses.
When given by IV: Vitamin B12 is LIKELY SAFE for most people. Vitamin B12 is considered safe, even in large doses.
When given as a shot: Vitamin B12 is LIKELY SAFE for most people. Vitamin B12 is considered safe, even in large doses.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Vitamin B12 is LIKELY SAFE for pregnant or breast-feeding women when taken by mouth in the amounts recommended. The recommended amount for pregnant women is 2.6 mcg per day. Breast-feeding women should take no more than 2.8 mcg per day. Don’t take larger amounts. The safety of larger amounts is unknown.
Post-surgical stent placement: Avoid using a combination of vitamin B12, folate, and vitamin B6 after receiving a coronary stent. This combination may increase the risk of blood vessel narrowing.
Allergy or sensitivity to cobalt or cobalamin: Do not use vitamin B12 if you have this condition.
Leber disease: Do not take vitamin B12 if you have this hereditary eye disease. It can seriously harm the optic nerve, which might lead to blindness.
Abnormal red blood cells (megaloblastic anemia): Megaloblastic anemia is sometimes corrected by treatment with vitamin B12. However, this can have very serious side effects. Don’t attempt vitamin B12 therapy without close supervision by your healthcare provider.
High numbers of red blood cells (polycythemia vera): The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera.
Interaction Rating=Major Do not take this combination.
Vitamin B12 is important for producing new blood cells. Chloramphenicol might decrease new blood cells. Taking chloramphenicol for a long time might decrease the effects of vitamin B12 on new blood cells. But most people only take chloramphenicol for a short time so this interaction isn’t a big problem.
Potassium: Potassium supplements can reduce absorption of vitamin B12 in some people and might contribute to vitamin B12 deficiency.
Vitamin C: Early research suggests that vitamin C supplements can destroy dietary vitamin B12. It isn’t known whether this interaction is important, but to stay on the safe side, take vitamin C supplements at least 2 hours after meals.
- The typical general supplemental dose of vitamin B12 is 1-25 mcg per day: The recommended dietary allowances (RDAs) of vitamin B12 are: 1.8 mcg; older children and adults, 2.4 mcg; pregnant women, 2.6 mcg; and breast-feeding women, 2.8 mcg. Because 10% to 30% of older people do not absorb food-bound vitamin B12 efficiently, those over 50 years should meet the RDA by eating foods fortified with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 mcg per day has been used to maintain vitamin B12 levels in older people.
- For vitamin B12 deficiency: Vitamin B12 doses of 300-10,000 mcg daily have been used. However, some evidence suggests that the most effective oral dose is between 647-1032 mcg daily.
- For high levels of homocysteine in the blood (hyperhomocysteinemia): Vitamin B12 doses of 400-500 mcg in combination with 0.54-5 mg of folic acid and 16.5 mg of pyridoxine has been used.
- For an eye disease that leads to vision loss in older adults (age-related macular degeneration or AMD): A combination of 1 mg of vitamin B12, 2.5 mg of folic acid, and 50 mg of pyridoxine daily has been used for 7.3 years.
APPLIED TO THE SKIN:
- For canker sores: A topical ointment containing vitamin B12 500 mcg daily in four doses for 2 days has been used.
AS AN INJECTION:
- For vitamin B12 deficiency: The usual dose is 30 mcg as an injection into the muscle or under the skin daily for 5-10 days. For maintenance therapy, 100-200 mcg once monthly is commonly used. Both cyanocobalamin and hydroxocobalamin forms are used. The usual dose for pernicious anemia-associated vitamin B12 deficiency is 100 mcg given as an injection into the muscle or under the skin once daily for 6-7 days. Then the dose may be given every other day for 7 doses followed by every 3-4 days for around 3 weeks. Then, 100 mcg should be injected every month for life. Another dosing recommendation for injectable vitamin B12 includes 1000 mcg daily for 7-10 days followed by 1000 mcg weekly for 1 month followed by 1000 mcg monthly for life.
- For rare inherited condition marked by vitamin B12 deficiency (Imerslund-Grasbeck disease): Vitamin B12 in the form of hydroxocobalamin has been injected into the muscle at a dose of 1 mg daily for 10 days followed by once monthly for the remainder of the person’s life.
- For cyanide poisoning: Hydroxocobalamin (Cyanokit) has been given intravenously (by IV) for a total dose of up to 10 grams.
USED IN THE NOSE:
- For vitamin B12 deficiency: Doses of 500 mcg of vitamin B12 have been injected into one nostril weekly.
APPLIED UNDER THE SKIN:
- For nerve pain caused by shingles (postherpetic neuralgia): As an injection under the skin, 1000 mcg of vitamin B12, with or without 100 mg of thiamine or 20 mg of lidocaine, has been given six times weekly for up to 4 weeks.
PLACED UNDER THE TONGUE:
- For canker sores: Vitamin B12 1000 mcg daily under the tongue for 6 months has been used.
- The recommended dietary allowances (RDAs) of vitamin B12 are: Infants 0-6 months, 0.4 mcg; infants 7-12 months, 0.5 mcg; children 1-3 years, 0.9 mcg; children 4-8 years, 1.2 mcg; children 9-13 years, and 1.8 mcg; older children.
AS AN INJECTION:
- For vitamin B12 deficiency: Injecting 0.2 mcg/kg of vitamin B12 into the muscle or under the skin once daily for 2 days, followed by a 1000 mcg injection daily for 2-7 days and another 100 mcg injection weekly for 4 weeks thereafter has been used. Additional injections of 100 mcg monthly may be needed depending on level of symptom improvement and cause of vitamin B12 deficiency.
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