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Methylcobalamin vs. cyanocobalamin

Difference between the most common sources of vitamin B12

The two primary forms of Vitamin B12 are methylcobalamin and cyanocobalamin. This article will focus on their key distinctions and the advantages they provide.

This article is based on scientific evidence, written by experts, and fact-checked by experts.
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Methylcobalamin vs. cyanocobalamin: What’s the difference?
Last updated on December 28, 2023, and last reviewed by an expert on June 6, 2023.

Cyanocobalamin and methylcobalamin are two variants of the vital vitamin B12. The former is a man-made version, while the latter occurs naturally, and the human body is capable of transforming the synthetic version into its natural counterpart.

Methylcobalamin vs. cyanocobalamin: What’s the difference?

Vitamin B12, otherwise known as cobalamin, is an essential water-soluble vitamin that plays a pivotal role in creating red blood cells, maintaining brain functionality, and synthesizing DNA.

Inadequate levels of this vital vitamin can lead to severe symptoms, encompassing exhaustion, nerve damage, gastrointestinal problems, and neurological issues such as depression and memory impairment.

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Given these potential issues, numerous people opt for vitamin B12 supplements to satisfy their nutritional requirements and thwart a deficiency.

This article will delve into the primary distinctions between methylcobalamin and cyanocobalamin, which are among the most prevalent sources of vitamin B12 in supplements.

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Synthetic vs. Natural

Vitamin B12 supplements are typically derived from two sources: cyanocobalamin or methylcobalamin.

Both are nearly identical and contain a cobalt ion surrounded by a corrin ring.

However, each has a different molecule attached to the cobalt ion. While methylcobalamin contains a methyl group, cyanocobalamin contains a cyanide molecule.

Cyanocobalamin is a synthetic form of vitamin B12 that’s not found in nature.

It’s used more frequently in supplements, as it’s more stable and cost-effective than other forms of vitamin B12.

When cyanocobalamin enters your body, it’s converted into either methylcobalamin or adenosylcobalamin, the two active forms of vitamin B12 in humans.

Unlike cyanocobalamin, methylcobalamin is a naturally occurring form of vitamin B12 that can be obtained through supplements and food sources like fish, meat, eggs, and milk.

Summary: Cyanocobalamin is a synthetic form of vitamin B12 found only in supplements, while methylcobalamin is a naturally occurring form that you can get through either food sources or supplements.

They may be absorbed and retained differently

Another major difference between methylcobalamin and cyanocobalamin is how they’re absorbed and retained within your body.

Some studies suggest that your body may absorb cyanocobalamin slightly better than methylcobalamin.

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One study found that people’s bodies absorbed about 49% of a 1-mcg dose of cyanocobalamin, compared to 44% of the same dose of methylcobalamin.

Conversely, another study comparing the two forms reported that about three times as much cyanocobalamin was excreted through urine, indicating that methylcobalamin may be retained better within your body.

However, some research suggests that differences in bioavailability between the two forms may be insignificant and that absorption could be influenced by factors such as age and genetics.

Unfortunately, recent research directly comparing these two forms of vitamin B12 is limited.

Additional studies are needed to measure the absorption and retention of methylcobalamin versus cyanocobalamin in healthy adults.

Summary: Research shows that cyanocobalamin may be absorbed better in your body, while methylcobalamin likely has a higher retention rate. Other studies have found that the differences in absorption and retention are minimal.

Both methylcobalamin and cyanocobalamin can be converted to other forms of vitamin B12

When you ingest cyanocobalamin, it can be converted to both active forms of vitamin B12, methylcobalamin, and adenosylcobalamin.

Much like methylcobalamin, adenosylcobalamin is essential to many aspects of your health.

It’s involved in the metabolism of fats and amino acids and the formation of myelin, which creates a protective sheath around your nerve cells.

Deficiencies in both forms of vitamin B12 can increase your risk of neurological issues and adverse side effects.

Both cyanocobalamin and methylcobalamin are reduced to a cobalamin molecule converted to the active forms of this vitamin within the body’s cells.

Suggested read: Water-soluble vitamins: A comprehensive overview

Some researchers recommended treating vitamin B12 deficiencies with either cyanocobalamin or a combination of methylcobalamin and adenosylcobalamin due to the distinct properties of these latter two forms.

Summary: While they differ in some aspects, both cyanocobalamin and methylcobalamin can be converted to other forms of cobalamin within the body.

Both forms have health benefits

Although distinct differences exist between methylcobalamin and cyanocobalamin, both have beneficial effects on health and can prevent B12 deficiencies.

One study found that treating seven B12-deficient people with oral methylcobalamin normalized vitamin B12 levels in their blood within just two months.

Similarly, another study showed that taking cyanocobalamin capsules for 3 months increased vitamin B12 levels in 10 people with pernicious anemia, a condition caused by impaired B12 absorption.

Both types of the vitamin may also provide other health benefits.

One review of seven studies showed that methylcobalamin and a B-complex containing cyanocobalamin effectively reduced symptoms of diabetic neuropathy, a complication of diabetes that leads to nerve damage.

Additionally, several animal studies have found that each form could have neuroprotective effects and may be beneficial in treating conditions that affect your nervous system.

Summary: Both methylcobalamin and cyanocobalamin can treat vitamin B12 deficiency. Animal and human studies have found that they could reduce symptoms of diabetic neuropathy and may also have neuroprotective effects.


If you think you may have a vitamin B12 deficiency, talk to your doctor to determine the best course of treatment.

However, if you’re looking to fill in the nutritional gaps in your diet, a vitamin B12 supplement may help.

Cyanocobalamin is a synthetic form of vitamin B12 that can be converted to the natural forms methylcobalamin and adenosylcobalamin.

The body may absorb cyanocobalamin better, while methylcobalamin has a higher retention rate.

Both can prevent B12 deficiency, but methylcobalamin should be combined with adenosylcobalamin for best results.

Suggested read: Can vitamin B12 help you lose weight?

Whether you choose which form of vitamin B12, combine it with a healthy, well-balanced diet to meet your nutritional needs and optimize your health.

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