Methylcobalamin vs. Cyanocobalamin: A Dietitian Explains

Methylcobalamin and cyanocobalamin are two different forms of vitamin B12. Although both are used in supplements and can increase B12 levels, they each have a different structure and source.

In additional to treating vitamin B12 deficiencies, methylcobalamin and cyanocobalamin treat health conditions such as pernicious anemia and nerve pain. Both forms are considered generally safe but may interact with certain medications.

Methylcobalamin vs. Cyanocobalamin

Methylcobalamin and cyanocobalamin are the two forms of vitamin B12 most commonly used in dietary supplements. Both provide health benefits but they differ in their structure and sources.

Because methylcobalamin and cyanocobalamin are most often used to increase vitamin B12 levels, it's essential to be familiar with recommended daily intakes.

The recommended dietary allowances (RDAs) for vitamin B12 are as follows:

• Birth to 6 months old: 0.4 micrograms (mcg)
• 7–12 months old: 0.5 mcg
• 1–3 years old: 0.9 mcg
• 4–8 years old: 1.2 mcg
• 9–13 years old: 1.8 mcg
• 14–18 years old: 2.4 mcg
• 19+ years old: 2.4 mcg

People who are pregnant or lactating require higher amounts of B12. During pregnancy, 2.6 mcg of vitamin B12 is recommended. While breastfeeding, 2.8 mcg of B12 is recommended.

Two Different Forms of Cobalamin

Methylcobalamin is a natural form of vitamin B12, and cyanocobalamin is synthetic. The two forms also differ in structure—methylcobalamin contains a methyl group, 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 eliminated from your body, so it isn't a concern.

Both forms of B12 are available in supplements, but 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 B12, it is found in animal-based foods like meat, fish, poultry, eggs, and dairy products.

Bioavailability and Absorption

During digestion, your 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 blood stream and is used by your body. When it comes to bioavailability, research results are mixed.

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

More research may be necessary regarding bioavailability, but both forms of B12 have been found to provide health benefits.

Health Benefits

Vitamin B12 is an essential nutrient, which 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 depends on the condition and your current B12 levels.

Who's at Risk of a B12 Deficiency?

Certain people may be at a higher risk of developing a vitamin B12 deficiency, including:

• Adults age 65 and older, often due to pernicious anemia, atrophic gastritis, and reduced production of enzymes
• People with pernicious anemia, an 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 untreated, a deficiency in B12 can lead to nerve damage. Therefore, early diagnosis of vitamin B12 deficiency is essential. A deficiency can also cause fatigue, megaloblastic anemia, dementia, weight loss, and infertility.

Special Considerations

Vitamin B12 supplements are generally safe, even in high doses because your body doesn't absorb the full amount. However, using methylcobalamin, cyanocobalamin, or 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 methylcobalamin, cyanocobalamin, and other B12 supplements, including:

• Proton pump inhibitors (omeprazole, esomeprazole, and lansoprazole)
• H2-receptor antagonists (cimetidine, famotidine, and ranitidine)
• Metformin
• Colchicine
• Cholestyramine
• Certain antibiotics (neomycin and chloramphenicol)

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

Summary

Methylcobalamin and cyanocobalamin are two forms of vitamin B12 used in supplements. While methylcobalamin is naturally found in foods, cyanocobalamin is synthetically produced. Cyanocobalamin is often preferred for supplements because it's less expensive and more stable.

In research, methylcobalamin and cyanocobalamin have beneficial effects on various health conditions, including B12 deficiency and pernicious anemia. They may also improve ALS, neuropathic pain, and other conditions. B12 supplements are generally considered safe but can interact with certain medicines.