Methylcobalamin vs. Cyanocobalamin: A Dietitian Explains

Two forms of vitamin B12 with similar health benefits, but different structures and bioavailability.

Medically reviewed by Allison Herries, RDN

Methylcobalamin and cyanocobalamin are two different forms of vitamin B12. Although both methylcobalamin and cyanocobalamin share similarities, each form of B12 is distinct in its purpose and structure.

Typically, methylcobalamin and cyanocobalamin treat vitamin B12 deficiencies, but other uses may exist. Both forms are considered generally safe but may interact with certain medications.

This article will compare methylcobalamin and cyanocobalamin, focusing on their bioavailability, health benefits, and potential side effects and interactions.

Methylcobalamin vs. Cyanocobalamin

Methylcobalamin and cyanocobalamin are the two forms of vitamin B12 most commonly used in dietary supplements.

Methylcobalamin and cyanocobalamin have similarities and differences. Though both are thought to provide health benefits, the two forms of B12 differ in their structures, absorption, and sources.

There is currently little strong evidence that one form is better, but some researchers argue that cyanocobalamin is superior.

There is a misconception regarding the safety of the cyanide found in cyanocobalamin. The truth is, that the amount of cyanide in cyanocobalamin is so small that it isn't a concern and has been deemed safe by scientists.

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

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

• Birth to 6 months old: 0.4 mcg (micrograms)

• 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 compound.

Both forms of B12 are found in supplements, but cyanocobalamin is used more often, possibly 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

Because of their differences in structure, methylcobalamin and cyanocobalamin are absorbed differently in your body.

During digestion, your body removes the methyl group from methylcobalamin or the cyanide molecule from cyanocobalamin, leaving a cobalamin molecule that can then be activated to a form of vitamin B12 that your body can use.

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.

Who's Most at Risk for B12 Deficiency?

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

• Adults ages 65 and older

• 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 gastrointestinal surgery

• Vegetarians and vegans

• Breastfed infants of vegan mothers

If left untreated, a deficiency in B12 can lead to neurological issues. Therefore, early diagnosis of vitamin B12 deficiency is essential.

Health Benefits

Vitamin B12 is an essential nutrient, which means you need it in varying amounts 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.

Research shows that B12 in its various forms (which include methylcobalamin and cyanocobalamin) provides certain health benefits. Some of the more prominent benefits of vitamin B12 are outlined below.

Vitamin B12 Deficiency

A vitamin B12 deficiency can occur if you don't get enough B12 through your diet or if you have certain conditions that reduce the absorption of B12.

A deficiency is typically treated with B12 supplements or intramuscular injections for several months or more. These treatments may contain methylcobalamin, but cyanocobalamin is more commonly used.

Evidence shows that both methylcobalamin and cyanocobalamin effectively correct a vitamin B12 deficiency. There is no compelling evidence that one form works better than the other.

Pernicious Anemia

Pernicious anemia is an autoimmune condition marked by an inability to absorb vitamin B12 properly. Pernicious anemia can lead to a severe vitamin B12 deficiency if left untreated.

Intramuscular injections of cyanocobalamin, methylcobalamin, or other forms of B12 are the hallmark treatment for pernicious anemia. Some research suggests that high-dose oral supplements that contain these forms of B12 may also be beneficial.

Although pernicious anemia can't be cured, lifelong use of vitamin B12 supplements or injections can treat it.

Amyotrophic Lateral Sclerosis

There is some evidence that methylcobalamin may treat symptoms of amyotrophic lateral sclerosis (ALS), a progressive neurological disease.

Research shows that methylcobalamin decreases levels of homocysteine, a potentially neurotoxic amino acid prevalent in ALS cases. This may translate to a slower progression of ALS.

One study found that people with newly diagnosed ALS may benefit from very high doses of methylcobalamin. In a 16-week trial, adults with ALS who took 50 milligrams (mg) of methylcobalamin experienced a 43% reduction in clinical deterioration related to their ALS.

Due to the novelty of this research, more studies of methylcobalamin for ALS are necessary.

Neuropathic Pain

Peripheral neuropathy is a medical condition in which nerves of the peripheral nervous system become damaged. This damage can happen for many reasons, including traumatic injury, diabetes, or a vitamin B12 deficiency, among others.

A prevalent symptom of peripheral neuropathy is pain. A systematic review found that supplementation with methylcobalamin and, to a lesser extent, cyanocobalamin may reduce neuropathic pain.

The review noted that vitamin B12 supplementation may work best for pain associated with certain kinds of peripheral neuropathy, including alcoholic neuropathy and diabetic neuropathy.

However, many of the studies included in the review were small and of poor design. More robust research would further prove the role of methylcobalamin and cyanocobalamin in managing peripheral neuropathy.

Special Considerations

Vitamin B12 is an essential nutrient that everyone needs. However, because it isn't widespread in foods (especially plant-based ones), some people must use dietary supplements to get enough of this vital nutrient.

As with any dietary supplement, using methylcobalamin, cyanocobalamin, or other B12 supplements may pose certain risks.

In general, vitamin B12 is thought to be safe, even in high doses. This is because your body doesn't store excess B12, so there's no concern for overdose or toxicity.

People with a cobalt allergy or sensitivity may need to limit their use of vitamin B12 supplements. This is because various forms of B12, including methylcobalamin and cyanocobalamin, contain cobalt. High intake of vitamin B12 may cause contact dermatitis in anyone with a cobalt allergy or sensitivity.

Methylcobalamin, cyanocobalamin, and other B12 supplements may interact with some popular medications.

Gastric acid inhibitors and metformin are two medications known to decrease the absorption of vitamin B12. 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 similar but different forms of vitamin B12. Though methylcobalamin is a natural type of B12, cyanocobalamin is synthetic.

In research, methylcobalamin and cyanocobalamin have beneficial effects on various health conditions, including B12 deficiency and pernicious anemia. They may each also offer benefits for ALS, neuropathic pain, and other conditions.

Vitamin B12 supplements are generally considered safe, but people taking certain medications may need to consider extra precautions regarding B12 intake.

Talk with a healthcare provider to learn more about methylcobalamin or cyanocobalamin.

Frequently Asked Questions

Is methylcobalamin better than cyanocobalamin?

Some research suggests that cyanocobalamin is better. Other research suggests methylcobalamin, a natural form of vitamin B12, is more bioavailable than cyanocobalamin, a synthetic form of B12. Overall, there isn't sufficient evidence to say that one form of B12 is better.

Which form of vitamin B12 is best?

There isn't a strong consensus as to which form of vitamin B12 is best when it comes to methylcobalamin or cyanocobalamin.

Both methylcobalamin and cyanocobalamin have been found to provide health benefits. After consumption, methylcobalamin and cyanocobalamin supplements are converted to active and usable forms of vitamin B12 in the body.

Who should not take methylcobalamin?

People with cobalt allergies may need to avoid (or at least limit) their use of methylcobalamin and other vitamin B12 supplements.

Methylcobalamin and other forms of vitamin B12 contain cobalt, a chemical that may cause allergies or sensitivities in some people. A person with a cobalt allergy or sensitivity should avoid taking large doses of vitamin B12 supplements because doing so may cause various skin reactions.

Read the original article on Verywell Health.