Vitamin B12


Vitamin B12, also known as cobalamin, is a water-soluble vitamin that is involved in the metabolism of every cell of the human body

April 8, 2019

Vitamin B12, also known as cobalamin, is a water-soluble vitamin that is involved in the metabolism of every cell of the human body. It is a co-factor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is particularly important in the normal functioning of the nervous system. It has a vital role in the synthesis of myelin, and in the maturation of developing red blood cells in the bone marrow.
Vitamin B12 is one of eight B vitamins which is an essential vitamin. Vitamin B12 can be found in foods such as meat, fish, and dairy products. As  there are no reliable vegetable sources of the vitamin, vegans must use a supplement or fortified foods for B12 intake or risk serious health consequences. It can also be made in a laboratory. It is often taken in combination with other B vitamins.
The most common cause of vitamin B12 deficiency in developed countries is impaired absorption due to a loss of gastric intrinsic factor, which must be bound to food-source B12 in order for absorption to occur. Those on long term antacid therapy, using proton pump inhibitors, H2 blockers or other antacids are at higher risk factor.

Uses & Effectiveness:

Effective for Treating:

Inherited Vitamin B12 deficiency (Imerslund-Grasbeck disease):

It is effective for treating people with an inherited disease that results in poor absorption of vitamin B12 by injecting as a shot for 10 days followed by monthly injections for the remainder of life.

Pernicious anemia:

It is effective for treating people having low red blood cell counts caused by poor absorption of vitamin B12 by injecting as a shot, as well as taking through the nose or by mouth.

Vitamin B12 deficiency:

It is effective for treating people with vitamin B12 deficiency by taking vitamin B12 by mouth, through the nose, or as a shot.
Injecting vitamin B12 into the muscle is better than taking it by mouth if vitamin B12 deficiency is severe or nerve damage is present.

Likely Effective for Treating:

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.

Hyperhomocysteinemia or High level of homocysteine in the blood:

Taking vitamin B12 by mouth, along with folic acid and sometimes pyridoxine (vitamin B6), can lower blood levels of homocysteine.
Possibly Effective for Treating:

Age-related macular degeneration (AMD):

Taking vitamin B12 with other B vitamins, including folic acid and vitamin B6, might help prevent an eye disease called age-related macular degeneration.

Nerve damage from shingles:

Injecting vitamin B12 in the form of methylcobalamin under the skin six times weekly for up to 4 weeks reduces pain  in people with nerve damage from shingles.
It is more effective than taking vitamin B12 by mouth or injecting lidocaine under the skin. It also reduces pain and the need for painkillers. Adding thiamine or lidocaine to the treatment also seems to reduce itching.

Canker sores:

Using an ointment containing vitamin B12 helps to reduce pain of canker sores.
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.

Possibly Ineffective for Treating:

Cancer:

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.

Sleep disorders:

Taking vitamin B12 by mouth does not seem to help people with sleep disorders.

Mental 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.

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.

Preventing falls:

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.

Performance in older people:

Taking folic acid with vitamin B12 doesn't seem to help older people. People who are already taking vitamin D walk better or have stronger hands.

Stroke:

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 for Treating:

Alzheimer's disease:

Higher vitamin B12 intake does not prevent Alzheimer's disease. However, 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's disease.

Clogged arteries:

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.

Preventing re-blockage of blood vessels after heart artery dilation (balloon angioplasty):

Taking folic acid plus vitamin B6 and vitamin B12 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.

Eczema (atopic dermatitis):

Aapplying 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.

Nerve pain due to cancer drugs:

Taking B vitamins that include vitamin B12 along with cancer drugs doesn't prevent nerve pain caused by cancer drugs.

Chronic obstructive pulmonary disease (COPD):

Taking vitamin B12 might improve endurance in people with COPD, a lung disease.

Nerve damage caused by diabetes:

Taking different forms of vitamin B12 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.

Colon and rectal cancer:

People who consume more vitamin B12 in their diet have a lower risk of developing colon or rectal cancer. However, taking vitamin B12 with folic acid and vitamin B6 daily for up to 7 years does not reduce the risk of developing colorectal cancer in women.

Depression:

Eating more food that contains vitamin B12 has been linked with a lower risk of depression in older men.

High triglyceride levels:

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 infant brains develop faster.

Diarrhea:

Taking twice the recommended daily allowance of vitamin B12, with or without folic acid, does not reduce the risk of diarrhea in children.

Fatigue:

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.

Hepatitis C:

Giving an injection of vitamin B12 in the form of cyanocobalamin every 4 weeks along with standard care can improve hepatitis C treatment.

Lower respiratory tract infections:

Taking twice the recommended daily allowance of vitamin B12, with or without folic acid, does not reduce the risk for lower respiratory tract infections in children.

Lung cancer:

There is no relationship between levels of vitamin B12 in the blood and the risk of lung cancer.

Peripheral neuropathy:

Taking a specific product containing vitamin B12 (Keltican) daily for 60 days reduces pain and also reduces the need for painkillers in people with nerve damage in parts of the body such as the hands and feet.

Blood clots in the veins:

Having low levels of vitamin B12 might be linked to an increased risk for blood clots in the veins.

Shaky-leg syndrome:

One form of vitamin B12 (cyanocobalamin) can help reduce tremors due to shaky-leg syndrome.

Tinnitus:

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.

Psoriasis:

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:

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.

More evidence is needed to rate the effectiveness of vitamin B12 for the below uses:

  • Aging.
  • Allergies.
  • Chronic fatigue syndrome (CFS).
  • Diabetes.
  • Heart disease.
  • Immune system problems.
  • Lyme disease.
  • Memory problems.
  • Multiple sclerosis.
  • Other conditions.

Side Effects & Safety:

Vitamin B12 is likely safe for most people when taken by mouth, applied to the skin, taken through the nose, administered as a shot, or injected into the vein (by IV). 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 not take more than 2.8 mcg per day.

Allergy or sensitivity to cobalt or cobalamin:

It is advisable not to use vitamin B12 if you have this condition.

Post-surgical stent placement:

Avoid taking a combination of vitamin B12, folate, and vitamin B6 after receiving a coronary stent. This combination may increase the risk of blood vessel narrowing.

Megaloblastic anemia:

Megaloblastic anemia or Abnormal red blood cells is sometimes corrected by treatment with vitamin B12. However, this can have very serious side effects. So, it is advisable not to take vitamin B12 therapy without close supervision of your healthcare provider.

Leber's 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.

Polycythemia vera:

The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera as it can reduce high numbers of red blood cells.

Interactions:

Do not take the below combination as it has Major Interaction with Vitamin B12.

Chloramphenicol interacts with Vitamin B12:

Vitamin B12 helps in 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. However, taking chloramphenicol for a short time will not cause any problem.

Dosing:

The following dose is recommended as per scientific research.

Adults:

By Mouth:

Because some older people can not absorb food-bound vitamin B12 efficiently due to many reasons, 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 is recommended to maintain vitamin B12 levels in older people. In general supplemental dose of vitamin B12 is 1-25 mcg per day.
The recommended dietary allowances (RDAs) of vitamin B12 are:

  • 1.8 mcg
  • 2.4 mcg for older children and adults
  • 2.6 mcg for pregnant women
  • 2.8 mcg for breast-feeding women.
  • 300-10,000 mcg daily for vitamin B12 deficiency
  • 400-500 mcg in combination with 0.54-5 mg of folic acid and 16.5 mg of pyridoxine for high blood levels of homocysteine
  • Combination of 1 mg of vitamin B12, 2.5 mg of folic acid, and 50 mg of pyridoxine daily for 7.3 years for preventing age-related macular degeneration (AMD).

Applied To The Skin:

  • A specific vitamin B12 0.07% cream (Regividerm) applied twice daily for atopic dermatitis (eczema)
  • A topical ointment containing vitamin B12 500 mcg daily in four doses for 2 days for canker sores
  • A specific cream (Regividerm, Regeneratio Pharma AG, Wuppertal, Germany) containing avocado oil plus vitamin B12 0.7 mg/gram applied for 12 weeks twice daily for psoriasis

As An Injection:

  • The usual dose is 30 mcg as an injection into the muscle or under the skin daily for 5-10 days for vitamin B12 deficiency. 100-200 mcg once monthly is commonly used for maintenance therapy. Both cyanocobalamin and hydroxocobalamin forms are used.
  • The usual dose is 100 mcg given as an injection into the muscle or under the skin once daily for 6-7 days for pernicious anemia-associated vitamin B12 deficiency.
  • The dose may be given every other day for 7 doses followed by every 3-4 days for around 3 weeks and then, 100 mcg should be injected every month for life as maintenance dose.
  • 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 a hereditary condition that causes vitamin B12 malabsorption called as Imerslund-Grasbeck disease.
  • Hydroxocobalamin (Cyanokit) has been given intravenously (by IV) for a total dose of up to 10 grams for cyanide poisoning.

Used In The Nose:

500 mcg of vitamin B12 have been injected into one nostril weekly for vitamin B12 deficiency.

Applied 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 as an injection under the skin for nerve damage from shingles.
  • 1000 mcg of vitamin B12 daily under the tongue for 6 months has been used for canker sores.

Children:

By Mouth:

The recommended dietary allowances (RDAs) of vitamin B12 are:

  • 0.4 mcg for Infants 0-6 months
  • 0.5 mcg for infants 7-12 months
  • 0.9 mcg for children 1-3 years
  • 1.2 mcg for children 4-8 years
  • 1.8 mcg for children 9-13 years and older children.

As An Injection:

Additional injections of 100 mcg monthly may be needed depending on level of symptom improvement and cause of 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 for vitamin B12 deficiency.