Methylcobalamin vs. Cyanocobalamin: Choosing a B12 Supplement

Methylcobalamin and cyanocobalamin are two different forms of vitamin B12 that have similar health benefits in preventing vitamin B12 deficiency. Methylcobalamin is a natural form of vitamin B12while cyanocobalamin is a synthetic form that your body turns into an active form of B12.

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Differences in Structure

Methylcobalamin and cyanocobalamin are the two forms of vitamin B12 most commonly used in dietary supplementsbut they differ in their structure and sources.

Methylcobalamin is a natural form of vitamin B12and cyanocobalamin is synthetic. The structure of both forms of vitamin B12 is a central cobalt ion with a corrin ring. The difference is that methylcobalamin contains a methyl group (one carbon and three hydrogen atoms)and cyanocobalamin contains a cyanide molecule.

There is a misconception regarding the safety of the cyanide found in cyanocobalamin. The truth is that the amount of cyanide is minuscule and is eliminated from your bodyso it isn't a concern.

Both forms of B12 are available in supplementsbut cyanocobalamin is used more often due to its lower cost and higher heat stability. Cyanocobalamin is also used to fortify certain foods to increase their value of vitamin B12.

Because methylcobalamin is a natural source of vitamin B12it is found in animal-based foods like meatfishpoultryeggsand dairy products.

Differences in Bioavailability and Absorption

During digestionyour body removes the methyl group from methylcobalamin or the cyanide molecule from cyanocobalamin. The remaining cobalamin molecule is absorbed and turned into an active form of vitamin B12 that your body can use (methylcobalamin).

Bioavailability refers to the amount of the vitamin that enters your bloodstream and is used by your body. When it comes to bioavailabilityresearch results are mixed.

According to one reviewmethylcobalamin and other natural sources of B12 are more bioavailable than synthetic forms like cyanocobalamin. Howevera small study from 2021 argues that differences in bioavailability between the two forms are negligible and that cyanocobalamin may maintain serum levels better.

Both Have Similar Health Benefits

Vitamin B12 is an essential nutrientwhich means you need to get it from food or supplements throughout your life. Your body can't make B12 on its own.

Vitamin B12 is vital to the function and development of your central nervous system and is necessary to make red blood cells and DNA.

Both forms of B12 provide health benefits by treating the following conditions:

• Vitamin B12 deficiency: A deficiency develops if you don't get enough B12 in your diet or can't absorb it.
• Pernicious anemia: This is an autoimmune condition that interferes with B12 absorption.
• Neuropathic pain: B12 may ease the pain caused by damaged peripheral nerves (peripheral neuropathy).
  
• Amyotrophic lateral sclerosis (ALS): B12 may slow the progression of this neurological disease.

The optimal dose and whether you need oral supplements or injections depend on the condition and your current B12 levels.

Supplements can be taken both orally and sublingually (under the tongue). Medical providers may recommend that people with anemia or malabsorption concerns take vitamin B12 sublingually.

Both Treat B12 Deficiency

Both forms of B12 are effective in treating B12 deficiency. Certain people may be at a higher risk of developing a vitamin B12 deficiencyincluding:

• Adults age 65 and olderoften due to pernicious anemiaatrophic gastritisand reduced production of enzymes
• People with pernicious anemiaan autoimmune condition that may cause gastric atrophy
• People with gastrointestinal disorders (like celiac disease and inflammatory bowel disease) that affect nutrient absorption
• Anyone who has had bariatric or gastrointestinal surgery
• Vegetarians and vegans (B12 is only found in animal-based foods)
• Breastfed infants of vegan mothers

If left untreateda deficiency in B12 can lead to nerve damage. Thereforeearly diagnosis of vitamin B12 deficiency is essential. A deficiency can also cause fatiguemegaloblastic anemiadementiaweight lossand infertility.

Special Considerations for Both

Vitamin B12 supplements are generally safeeven in high doses because your body doesn't absorb the full amount. Howeverusing methylcobalamincyanocobalaminor other B12 supplements may pose the following risks:

Cobalt Allergy

People with a cobalt allergy or sensitivity should talk with a healthcare provider before using vitamin B12 supplements. All forms of B12 contain cobalt (cobalamin). Taking vitamin B12 may cause contact dermatitis if you have a severe allergy.

Medication Interactions

Certain medications reduce the absorption of methylcobalamincyanocobalaminand other B12 supplementsincluding:

• Proton pump inhibitors (omeprazoleesomeprazoleand lansoprazole)
• H2-receptor antagonists (cimetidinefamotidineand ranitidine)
• Metformin
• Colchicine
• Cholestyramine
• Certain antibiotics (neomycin and chloramphenicol)

If you use these or other medicationstalk with a healthcare provider about ways to maintain healthy levels of B12.

Key Takeaways

• Methylcobalamin and cyanocobalamin are two forms of vitamin B12 that have similar health benefitsincluding preventing and treating B12 deficiency.
• While methylcobalamin is naturally found in foodscyanocobalamin is synthetically produced.
• Cyanocobalamin is often preferred for supplements because it's less expensive and more stable.