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 taken by mouth to treat and prevent vitamin B12 deficiency, a condition in which vitamin B12 levels in the blood are too low.
Vitamin B12 is also taken by mouth for memory loss, Alzheimer's disease, to slow aging, and to boost mood, energy, concentration, mental function, and the immune system. It is also used for heart disease, clogged arteries and decreasing the risk of re-clogging arteries after surgery, high triglyceride levels, lowering high homocysteine levels (which may contribute to heart disease), male infertility, diabetes, diabetic nerve damage, nerve damage in the hands or feet, sleep disorders, depression, mental disorders, schizophrenia, weak bones (osteoporosis), swollen tendons, AIDS, inflammatory bowel disease, diarrhea, asthma, allergies, a skin disease called vitiligo, and skin infections.
Some people use vitamin B12 by mouth for amyotrophic lateral sclerosis (Lou Gehrig's disease), multiple sclerosis, preventing the eye disease age-related macular degeneration (AMD), a condition in which the body products too much thyroid hormone, Lyme disease and gum disease. It is also used by mouth for respiratory tract infections, maintaining fertility, ringing in the ears, bleeding, liver and kidney disease, canker sores, preventing fractures, preventing stroke, preventing blood clots, and for protection against the poisons and allergens in tobacco smoke. It is also taken by mouth to prevent cancer, including breast cancer, cervical cancer, colorectal cancer, pancreatic cancer, and lung cancer. Vitamin B12 is also used to prevent broken bones and falls, and cataracts. It is also used to help people with a lung disease called chronic obstructive pulmonary disease (COPD) exercise longer.
Vitamin B12 is applied to the skin either alone or in combination with avocado oil for psoriasis and eczema. Also, a vitamin B12 nasal gel is applied for pernicious anemia and preventing and treating vitamin B12 deficiency.
Vitamin B12 is injected into the body to prevent and treat vitamin B12 deficiency. It is also used for tremors, to treat Imerslund-Grasbeck disease, cyanide poisoning, nerve damage caused by shingles, diabetic nerve damage, ringing in the ears, tiredness or fatigue, chronic fatigue syndrome, hepatitis C, a condition in which the body products too much thyroid hormone, bleeding, cancer, psoriasis, and liver and kidney disease. It is also injected in the body to prevent arteries from re-clogging after surgery.
Vitamin B12 is breathed in for canker sores.
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:
Likely Effective for...
Possibly Effective for...
Possibly Ineffective for...
Insufficient Evidence to Rate Effectiveness for...
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.
The following doses have been studied in scientific research:
The typical general supplemental dose of vitamin B12 is 1-25 mcg per day.
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.
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