Vitamin B12

Other Names

  • B-12
  • B Complex Vitamin
  • Bedumil
  • Cobalamin
  • Cobalamine
  • Cobamin
  • Complexe Vitaminique B
  • Cyanocobalamin
  • Cyanocobalaminum
  • Cycobemin
  • Hydroxocobalamin
  • Hydroxocobalaminum
  • Hydroxocobémine
  • Idrossocobalamina
  • Vitadurin
  • Vitadurine
  • Vitamine B12

Dietary Sources

  • Meat
  • Fish
  • Dairy products

Recommended Use

  1. Treating and preventing vitamin B12 deficiency
  2. Treating pernicious anemia, a serious type of anemia that is due to vitamin B12 deficiency and is found mostly in older people.
  3. Memory loss
  4. Alzheimer’s disease
  5. Boosting mood, energy, concentration and the immune system
  6. Slowing aging
  7. For heart disease, lowering high homocysteine levels (which may contribute to heart disease)
  8. Male infertility
  9. Diabetes
  10. Sleep disorders
  11. Depression
  12. Mental disorders
  13. Weak bones (osteoporosis)
  14. Swollen tendons
  15. AIDS
  16. Inflammatory bowel disease
  17. Asthma
  18. Allergies
  19. A skin disease called vitiligo
  20. Preventing cervical and other cancers
  21. Skin infections
  22. Amyotrophic lateral sclerosis (Lou Gehrig’s disease)
  23. Multiple sclerosis
  24. Preventing the eye disease age-related macular degeneration (AMD), Lyme disease and gum disease.
  25. Ringing in the ears
  26. Bleeding
  27. Liver and kidney disease
  28. Protection against the poisons and allergens in tobacco smoke.
  29. Vitamin B12 is applied to the skin either alone or in combination with avocado oil for psoriasis and eczema.
  30. Vitamin B12 is frequently used in combination with other B vitamins in various vitamin B complex products.

Effectiveness of B12

  • 1- Inherited 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.
  • 2- Pernicious anemia
  • Injecting vitamin B12 as a shot, as well as taking through the nose or by mouth, is effective for treating low red blood cell counts caused by poor absorption of vitamin B12.

  • Vitamin B12 deficiency
      • Taking vitamin B12 by mouth, through the nose, or as a shot is effective for treating vitamin B12 deficiency.

      • 4- 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).
      • 5- High level of homocysteine in the blood (Hyperhomocysteinemia)
      • Oral B12 along with folic acid and sometimes pyridoxine (vitamin B6), can lower blood levels of homocysteine.

      • 6- An eye disease called age-related macular degeneration (AMD)
      • Taking vitamin B12 with other vitamins, including folic acid and vitamin B6, may help prevent an eye disease called age-related macular degeneration.

      • 7- Eczema (atopic dermatitis)
      • Applying a vitamin B12 cream (Regividerm) to the affected area twice daily may help treat eczema.

      • 8- Breast cancer
      • Vitamin B12 may reduce the risk of breast cancer when taken with folate, vitamin B6, and methionine.

      • 9- Canker sores
      • Taking vitamin B12 1000 mcg under the tongue (sublingually) may help reduce the number of canker sore outbreaks, the duration of outbreaks, and pain caused by the canker sores.

      • 10- Nerve damage caused by diabetes
      • 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.
      • 11- Fatigue
      • Shots containing 5 mg of vitamin B12 twice weekly may improve general well-being and happiness in people with fatigue.
      • 12- High triglyceride levels
      • Taking 7.5 mcg of vitamin B12 together with 5 grams of fish oil may be more effective then fish oil alone when used daily to reduce total cholesterol and triglyceride levels.
      • 13- 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.
      • 14- Shaky-leg syndrome
      • One form of vitamin B12 (cyanocobalamin) can help reduce tremors due to shaky-leg syndrome.


      Vitamin B12 is safe for most people when:

      • Taken by mouth
      • Applied to the skin
      • Taken through the nose
      • Administered as a shot

      Precautions & Warnings

    1. Pregnancy and breast-feeding
      • Vitamin B12 is 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

    2. High numbers of red blood cells (polycythemia vera)
      • The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera

    3. 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.

    4. Leber’s disease, a hereditary eye disease
      • Do not take vitamin B12 if you have this disease.
      • It can seriously harm the optic nerve, which might lead to blindness.

    5. Allergy or sensitivity to cobalt or cobalamin
      • Do not use vitamin B12 if you have this condition

    6. 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.

      B12 Interactions with Medications

      Major “Do not take this combination”

    7. Chloramphenicol
      • Vitamin B12 is important for producing new blood cells.
      • Chloramphenicol may 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.

      B12 Interactions with Herbs and Supplements

    8. Folic acid
      • Folic acid, particularly in large doses, can cover up vitamin B12 deficiency, and cause serious health effects.
      • Be sure that your healthcare provider checks your vitamin B12 levels before you start taking folic acid.

    9. Potassium
      • Potassium supplements can reduce absorption of vitamin B12 in some people and may contribute to vitamin B12 deficiency.

    10. Vitamin C
      • 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.

      B12 Interactions with Foods

    11. Alcohol
      • Heavy drinking for at least a two-week period can decrease vitamin B12 absorption from the gastrointestinal tract.

      Recommended Doses

      • 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, 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 or pernicious anemia: cyanocobalamin doses of 300-10,000 mcg (microgram) daily have been used.
      • However, some evidence suggests that the most effective oral dose is between 647-1032 mcg/day.
      • For high blood levels of homocysteine: vitamin B12 500 mcg in combination with 0.5-5 mg folic acid and 16.5 mg pyridoxine has been used.
      • For preventing age-related macular degeneration (AMD): vitamin B12 1 mg, folic acid 2.5 mg, and pyridoxine 50 mg daily has been studied.


      • For atopic dermatitis (eczema): a specific vitamin B12 0.07% cream (Regividerm) applied twice daily has been used.
      • For psoriasis: 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 has been used.