Natural Standard® Patient Monograph, Copyright © 2014 (www.naturalstandard.com). All Rights Reserved. Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Background
Vitamin B12 is an essential water-soluble vitamin that is commonly found in a variety of foods, such as fish, shellfish, meat, eggs, and dairy products. Vitamin B12 is frequently used in combination with other B vitamins in a vitamin B complex formulation. Vitamin B12 is important in DNA synthesis. Vitamin B12 is bound to the protein in food. Acid in the stomach releases B12 from protein during digestion. Once released, B12 combines with a substance called intrinsic factor (IF) before it is absorbed into the bloodstream.
The human body stores several years’ worth of vitamin B12 in the liver, so low levels in the body are rare. Decreases in vitamin B12 levels are more common in the elderly, HIV-infected persons, and vegetarians. Inability to absorb vitamin B12 from the intestinal tract can cause a type of anemia called pernicious anemia. Fever and symptoms of “excessive sweating” have been reported with anemia due to low levels of vitamin B12; however, these are fixed with vitamin B12 treatment.

Related terms
Adenosylcobalamin, AdoB12, B complex, B complex vitamin, B-12, bedumil, cobalamin, cobalamins, cobamin, cyanocobalamin, cyanocobalamine, cyanocobalaminum, cycobemin, hydroxocobalamin, hydroxocobalaminum, hydroxocobemine, idrossocobalamina, mecobalamin, methylcobalamin, vitadurin, vitamin B-12, vitamina B12 (Spanish), vitamine B12 (French).

Dosing
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)
Recommended dietary amounts (RDAs) are 2.4 micrograms daily for ages 14 years and older, 2.6 micrograms daily for pregnant females, and 2.8 micrograms daily for breastfeeding females. Those over 50 years of age should meet the RDA by eating foods reinforced with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 micrograms daily has been used to maintain vitamin B12 levels in older people. A doctor and a pharmacist should be consulted for use in other indications.

For canker sores, sublingual (under the tongue) vitamin B12 has been given daily for six months.
For claudication, a total daily dose of 1.5 milligrams of vitamin B12 was taken by mouth in divided doses of 0.5 miligrams three times daily for six months.
For vitamin B12 deficiency, 125-2,000 micrograms of cyanocobalamin has been taken by mouth daily for up to 2.5 years or longer. Five hundred micrograms of sublingual (under the tongue) vitamin B12 has been used daily for up to four weeks. The following doses have been given intravenously (through the veins): 1,000 micrograms of intramuscular cobalamin once daily for 10 days (after 10 days, the dose was changed to once weekly for four weeks, followed by once monthly for life); 1,000 micrograms of intramuscular cyanocobalamin given on days 1, 3, 7, 10, 14, 21, 30, 60, and 90 of treatment. For vitamin B12 deficiency caused by long-term PPI therapy, cyanocobalamin nasal spray has been used for eight weeks. The exact dosage is unclear. One study tested intranasal vitamin B12 replacement therapy (500 micrograms weekly).

For prevention of anemia, the following doses have been taken by mouth: 2-10 micrograms of vitamin B12 daily combined with iron and/or folic acid for up to 16 weeks; 100 micrograms of vitamin B12 every other week plus daily folic acid and/or iron for up to 12 weeks.

For mental performance, the following doses have been taken by mouth: 0.05-1 milligram vitamin B12 taken daily for four weeks to 5.4 years; 10 micrograms or 50 micrograms of cyanocobalamin daily for one month; and one milligram of cyanocobalamin weekly for four weeks. One 1,000 microgram vitamin B12 injection has been used daily for five days, followed by one 1,000 microgram injection monthly for five months. Additionally, 1000 microgram injections have been used weekly for four weeks or monthly for six months.

For cyanide poisoning, an intravenous (IV) infusion of five grams of hydroxocobalamin (up to 20 grams) has been used.
For depression, one milligram of cyanocobalamin, through intramuscular injections, was used weekly for four weeks.
For hereditary sideroblastic anemia, 100 micrograms of intramuscular vitamin B12 has been used monthly, with or without daily folic acid, for up to four months.
Children (under 18 years old)

Recommended dietary amounts (RDAs) are lacking for all age groups; therefore, adequate intake (AI) levels have been used instead. The RDAs and AI levels of vitamin B12 are as follows: for infants 0-6 months old, 0.4 micrograms (AI); for infants 7-12 months old, 0.5 micrograms (AI); for children 1-3 years old, 0.9 micrograms; for children 4-8 years old, 1.2 micrograms; and for children 9-13 years old, 1.8 micrograms.

Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies
Vitamin B12 supplements should be avoided in people sensitive or allergic to vitamin B12, cobalt, or any other product ingredient.

Side Effects and Warnings
Vitamin B12 is likely safe when taken according to the recommended dietary amounts (RDA) or less.
Use cautiously in people with heart concerns, due to an increase in rates of restenosis (reoccurrence of narrowing of a blood vessel) after stent placement and vitamin B12 supplementation.

Use cautiously in people with high blood pressure, as high blood pressure following intravenous (IV) administration of hydrocobalamin has been reported.
Use cautiously in people with a history of cancer.
Use cautiously in people with skin disorders, as rash, itching, and burning have been reported. Pink or red skin discoloration and facial flushing have also been reported.
Use cautiously in people with genitourinary concerns, as urine discoloration has been reported.

Use cautiously in people with gastrointestinal concerns, as nausea, difficulty swallowing, and diarrhea have been reported.
Use cautiously in people with blood disorders, as it has been reported that treatment of vitamin B12 deficiency may lead to an increase in blood volume and the number of red blood cells.

Use cautiously in people with low serum levels of potassium, as the correction of megaloblastic anemia with vitamin B12 may result in fatally low potassium levels.
Use cautiously in people with a history of gout, or elevated uric acid levels, as the correction of megaloblastic anemia with vitamin B12 may start a gout attack.

Use cautiously in people taking the following agents, as they have been associated with reduced absorption or reduced serum levels of vitamin B12: ACE inhibitors, acetylsalicylic acid (aspirin), alcohol, antibiotics, anti-seizure agents, bile acid sequestrants, chloramphenicol, colchicine, H2 blockers, metformin, neomycin, nicotine, nitrous oxide, oral contraceptives, para-aminosalicylic acid, potassium chloride, proton pump inhibitors (PPIs), tobacco, vitamin C, and zidovudine (AZT, Combivir®, Retrovir®).
Avoid in people sensitive or allergic to vitamin B12, cobalt, or any other product ingredient.

Pregnancy and Breastfeeding
Vitamin B12 is likely safe when taken according to the recommended dietary amounts (RDA) or less. There is insufficient reliable information available about the safety of larger amounts of vitamin B12 during pregnancy.

Infants, when breastfed by a vitamin B12-deficient mother, are at risk for many health issues such as severe developmental disorders, growth failure, and anemia. Some research has reported that vitamin B12 levels during pregnancy have effects on mental function in infants.

Interactions

Interactions with Drugs
Vitamin B12 may interact with agents for bone loss, cancer, gout (colchicine), high blood pressure (angiotensin-converting enzyme inhibitors), and for stomach and intestine disorders (H2 blockers, proton pump inhibitors), agents that affect blood products, agents that affect the nervous system, alcohol, Alzheimer’s agents, antibiotics (neomycin), anti-seizure agents, aspirin, bile acid sequestrants, birth control pills, cardiovascular agents, chloramphenicol, metformin, nicotine, nitrous oxide, para-aminosalicylic acid, stimulants, and zidovudine.

Interactions with Herbs and Dietary Supplements
Vitamin B12 may interact with herbs and supplements for bone loss, cancer, cholesterol, gout, high blood pressure, and for stomach and intestine disorders, herbs and supplements that affect blood products and that affect the nervous system, Alzheimer’s herbs and supplements, antibacterials, anti-seizure herbs and supplements, birth control, cardiovascular herbs and supplements, folic acid, omega-3 fatty acids, potassium, salicylates, stimulants, tobacco, and vitamin C.

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