Vitamin B12 is a vitamin. It can be found in foods such as meat, fish, and dairy products. It can also be made in a laboratory.
Vitamin B12 is used for treating and preventing vitamin B12 deficiency, a condition in which vitamin B12 levels in the blood are too low. It is also used to treat pernicious anemia, a serious type of anemia that is due to vitamin B12 deficiency and is found mostly in older people. For this purpose, people use either a supplement that is taken by mouth or a gel that is applied inside the nose.
Vitamin B12 is also used for memory loss; Alzheimer’s disease; boosting mood, energy, concentration and the immune system; and slowing aging. It is also used for heart disease, lowering high homocysteine levels (which may contribute to heart disease), male infertility, diabetes, sleep disorders, depression, mental disorders, weak bones (osteoporosis), swollen tendons, AIDS, inflammatory bowel disease, asthma, allergies, a skin disease called vitiligo, preventing cervical and other cancers, and skin infections.
Some people use vitamin B12 for amyotrophic lateral sclerosis (Lou Gehrig’s disease), multiple sclerosis, preventing the eye disease age-related macular degeneration (AMD), Lyme disease and gum disease. It is also used for ringing in the ears, bleeding, liver and kidney disease, and for protection against the poisons and allergens in tobacco smoke.
Vitamin B12 is applied to the skin either alone or in combination with avocado oil for psoriasis and eczema.
Vitamin B12 is frequently used in combination with other B vitamins in various vitamin B complex products.
Natural Medicines rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for VITAMIN B12 are as follows:
More evidence is needed to rate the effectiveness of vitamin B12 for these uses.
Vitamin B12 is LIKELY SAFE for most people when taken by mouth, applied to the skin, taken through the nose, or administered as a shot.
Mild itching has been reported in one person who used a specific avocado oil plus vitamin B12 cream for psoriasis.
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.
High numbers of red blood cells (polycythemia vera): The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera.
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.
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.
Allergy or sensitivity to cobalt or cobalamin: Do not use vitamin B12 if you have this condition.
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.
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.
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.
Potassium supplements can reduce absorption of vitamin B12 in some people and might contribute to vitamin B12 deficiency.
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.
Heavy drinking for at least a two-week period can decrease vitamin B12 absorption from the gastrointestinal tract.
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