Vitamin B12

Cyanocobalamin, or vitamin B12, is a water-soluble vitamin that cannot be stored in the body. Excess vitamin B12 is passed out of the body through the urine. Vitamin B12 is available as a supplement, and it can be found in animal food sources such as meat, fish, beef liver, clams, eggs, and diary products. Vitamin B12 is often used in combination with other B vitamins in a vitamin B complex formulation.

vitamin B12, cyanocobalamin

vitamin B12

Vitamin B12 is usually taken by mouth. It is available in different forms, including chewable tablets and gummies, capsules, tablets, powders, strips, drops, and liquids. Vitamin B12 is also available in an injectable form to be given subcutaneously (into skin fat), intramuscularly (into muscles), or intravenously (into veins).

Table 1 lists the usual dose range and the recommended dietary allowance (RDA) for vitamin B12 for different age groups. People with vitamin B12 deficiency might need doses at or above the RDA.

Table 1. Usual daily dose range and RDA for vitamin B12 for different age groups

Injectables are usually dosed at 250 µg to1000 µg monthly.

Keep in mind that cobalt supplements and vitamin B12 supplements will both contribute to your daily vitamin B12 intake. You should reduce your use of vitamin B12 products in such cases. Let your health care provider know about all other supplements that you may be taking.

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

Vitamin B12 is important in maintaining overall good health. It helps the body to form red blood cells and to metabolize carbohydrates, fats, and proteins. It is important for the proper function and development of the brain and nerves.

At doses at or above the RDA, vitamin B12 supplementation is highly effective for preventing and treating vitamin B12 deficiency and associated diseases such as pernicious anemia (a type of anemia due to vitamin B12 deficiency). Some people may have low vitamin B12 levels because of absorption problems or inadequate amounts in their diet (for example, vegetarians are at risk since vitamin B12 is available only from animal food sources). Vitamin B12 supplementation in these cases can help prevent vitamin B12 deficiency.

Vitamin B12 has also been studied to prevent heart diseases and to treat Alzheimer’s disease, memory loss, male infertility, diabetes, mental disorders, inflammatory bowel disease, asthma, fatigue, and high cholesterol. However, there is not enough reliable evidence for these uses; additional studies are required to confirm the benefits of vitamin B12 in these conditions.

Vitamin B12 has also been studied together with folic acid and vitamin B6 for prevention of recurrent strokes and breast cancer. However, research has shown that this combination of supplements did not lower the risk of stroke or breast cancer.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

Vitamin B12 is generally well tolerated by most people if taken in recommended amounts.

People who are allergic or sensitive to cobalt or cobalamin should consult their health care provider before taking vitamin B12 supplements.

People with anemia need to talk to their health care provider about what treatment is right for them before starting any type of vitamin supplementation. Taking vitamin B12 supplements before a proper diagnosis from the doctor may make it harder for your doctor to diagnose the type of anemia you have.

Vitamin B12 is safe for pregnant or breast-feeding women when taken by mouth in recommended amounts.

Certain medications may reduce your intake of vitamin B12. These include:

• aminosalicylic acid
• acetylsalicylic acid (ASA)
• carbamazepine
• colchicine
• H2 blockers (e.g., ranitidine, famotidine)
• metformin
• phenobarbital
• phenytoin
• proton pump inhibitors (e.g., lansoprazole, pantoprazole)

Heavy drinking for more than 2 weeks can also decrease vitamin B12 absorption.

Consult your health care provider before taking vitamin B12 supplements if you have:

• any stent operations done previously
• an allergy to cobalamin or cobalt

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.

1. Health Canada. Drugs and Health Products. Multi-Vitamin/Mineral Supplements Monograph. https://webprod.hc-sc.gc.ca/nhpid-bdipsn/atReq.do?atid=multi_vitmin_suppl&lang=eng.
2. Natural Medicines Comprehensive Database. Vitamin B12.