Methylcobalamin Vs. Cyanocobalamin: Which B12 To Take?

Vitamin B12 is essential for our health and any deficiency should be treated with a B12 supplement. We look at methylcobalamin versus cyanocobalamin, which B12 to take for optimum benefit.

Methylcobalamin Vs. Cyanocobalamin Which B12 To Take

This water soluble vitamin is vital to many of our bodily processes so maintaining a good level in your system is very important for your health and wellbeing.

We look at the natural form of B12 versus its synthetic form and how both are absorbed and retained. We will also consider the difference in health benefits and the correct dosage of each.

Natural Vs Synthetic

Vitamin B12 is most commonly available in two forms, methylcobalamin and cyanocobalamin. Cyanocobalamin is a synthetic form of the vitamin found in supplements and methylcobalamin is found in animal food products. 

Those who struggle with malabsorption of natural B12 may benefit from the synthetic form of cyanocobalamin. 


Methylcobalamin is a naturally occurring B12 vitamin that is found in animal products such as meat, fish, milk and eggs. It can also be taken as a supplement either by injection or as a tablet or capsule. 

When you take methylcobalamin it is converted into an active form that can be circulated and used by the body. This is called bio-availability. Methylcobalamin has a methyl group in the form of carbon and hydrogen atoms. 

Methylcobalamin is used by the brain, liver and nervous system and is thought to be more beneficial to the health and repair of nerves and brain cells than cyanocobalamin. 

There are certain conditions that people may suffer from which requires them to take a B12 supplement such as pernicious anemia, or those who follow a vegetarian or vegan diet. 

Vegetarians and vegans will not be able to take methylcobalamin however as it is derived from animal products. Those following a vegan or vegetarian diet can take cyanocobalamin instead which is a synthetic version of B12. 


Cyanocobalamin is formed through a synthetic process and contains a cyanide molecule. However, the amount of cyanide is very small and is processed by the liver. 

Once the cyanide molecule is removed cyanocobalamin becomes methylcobalamin or adenosylcobalamin. Adenosylcobalamin, along with hydroxocobalamin are the other forms of vitamin B12. 

When the cyano compound is removed from cyanocobalamin, a methyl group is added, and it becomes methylcobalamin. 

Synthesizing B12 as cyanocobalamin means that the vitamin becomes more stable, has a longer shelf life and is more cost effective. It is also suitable for vegetarians and vegans who are one of the groups most at risk of suffering from a B12 deficiency. 

Vitamin B12 in the form of cyanocobalamin can be taken as an injection or as a capsule or tablet. 

Absorption & Retention

With different types of B12 available as supplements it may be difficult to understand how they vary from each other and which is best suited to your needs. 

One way of differentiating between cyanocobalamin and methylcobalamin is in the way that they are both absorbed and retained by the body. 

What Is Bio-Availability?

For a substance to be bioavailable it has to reach its intended biological destination. This is done through reaching the systemic circulation and some substances do this more readily than others. 

In the case of methylcobalamin and cyanocobalamin, it is the former, naturally occurring variation that is more readily bioavailable.

Cyanocobalamin has to go through a process of being stripped of its cyanide molecule and gain a methyl group before it can do its work. 


Some studies have suggested that despite being a synthetically produced variation of vitamin B12 cyanocobalamin is more readily absorbed by the body. 

In one study 49% of a 1-mcg dose of cyanocobalamin was absorbed in comparison to 44% of the same dosage of methylcobalamin. 


Although cyanocobalamin seems to be more readily absorbed by the body, a study showed that three times as much of this variation of vitamin B12 is excreted in the urine than the naturally occurring methylcobalamin. 

This would seem to indicate that methylcobalamin is more effectively retained by the body than the synthetic cyanocobalamin. 

More research is needed to determine the differences in the absorption and retention of both these types of vitamin B12 as factors such as age and genetics may influence the outcomes. 

Conditions That Affect B12 Levels

There are certain conditions that affect the absorption of vitamin B12 in its natural form. 

Pernicious Anemia

This is an autoimmune condition that causes antibodies to attack the lining of the stomach and nerve cells. As a result your body’s ability to absorb vitamin B12 is affected.

The antibodies also attack proteins called intrinsic factor which transport B12 in your bloodstream. The treatment for pernicious anemia is a supplement of cyanocobalamin. 

Malabsorption Following Gastrointestinal Surgery

Certain types of gastrointestinal surgery can interfere with the body’s ability to absorb vitamin B12 in its natural form, such as methylcobalamin. Some gastric bypass surgeries can affect the cells that permit B12 absorption. 

Surgery that removes part of the small intestine will also hinder the absorption of B12. This in turn can cause the development of pernicious anemia. 

Side Effects Of Medication

Certain medications such as those used for the treatment of diabetes and epilepsy can affect the level of vitamin B12 in your body. Some antibiotics prescribed to treat infections may also have an impact on levels of B12. 


Fish that is undercooked can result in a tapeworm infection. Tapeworms feed on B12 and this will result in the level of B12 in your body being low. 

Crohn’s Disease & Graves Disease

Medical conditions such as Crohn’s disease, or celiac disease make it very difficult for the body to absorb enough vitamin B12.

Other autoimmune diseases such as Graves disease and hypoparathyroidism also increase your chances of developing pernicious anemia. 

Lifestyle Choices

Those who choose to follow a vegan or vegetarian diet are at higher risk than most groups of developing a deficiency of vitamin B12.

This is because naturally occurring B12 is found only in animal products. Vegans and vegetarians need to take cyanocobalamin as a supplement. 

Health Benefits

Health Benefits

There are many different health benefits to taking a vitamin B12 supplement or to including the natural form into your daily diet. 

Red Blood Cell Production

Vitamin B12 is essential for the proper production of healthy red blood cells. When there is a lack of these blood cells a vitamin B12 deficiency is typically the reason. 

As red blood cells carry oxygen throughout the body a deficiency of B12 has serious consequences if not addressed properly. Taking cyanocobalamin or methylcobalamin as a supplement will increase the production and health of your red blood cells. 

Nerve & Brain Cell Protection

B12 is necessary for the production of myelin which is the protective covering of nerves. If this sheath is damaged it can slow the transmission of electrical signals along the nerves.

With the help of a vitamin B12 supplement this damage can be repaired and the speed of the nerve signals. 

Methylcobalamin has been found to be effective in the regeneration of axonal nerves and has neuroprotective properties. It is also approved as a treatment for peripheral neuropathy. B12 works in combination with folate to protect and facilitate nerve and brain cell health. 

Support Immune Function

Vitamin B12 has a vital role in the support of your immune system. In those suffering from a B12 deficiency the number of lymphocytes is reduced and hinders the activity of natural killer cells. 

Intramuscular injections of methylcobalamin or cyanocobalamin restores the production of lymphocytes and increases the activity of natural killer cells which are important in the protection against cancer. 

Protect DNA & RNA

The synthesis of DNA relies on good levels of vitamin B12 and a deficiency can result in alterations in this synthesis and damage to DNA. Neurological disorders, cardiovascular disease and some cancers have been linked to low B12 serum levels. 

Taking a B12 supplement such as cyanocobalamin or including foods rich in naturally occurring methylcobalamin is important to protect your DNA and RNA. 

Heart Health

The role of B12 in heart health comes from its role in maintaining optimal homocysteine balance. This amino acid is essential in supporting cardiovascular and arterial health. B12 along with B6 and folate break it down to form other chemicals that your body requires. 

If there is too much homocysteine in your body the excess can cause damage to the arterial linings. It can also create blood clots or even blockages in the blood vessels. So having enough B12, along with folate and B6 is essential to break down the homocysteine. 



The recommended daily amount of vitamin B12 is based on how much is needed for hematological stasis and B12 serum values. This is 2.4 micrograms per day and includes an assumed absorption rate of 50%. 

This dosage is for the majority of people who can absorb B12. However, there is a percentage of people, normally over the age of 50 who have absorption issues with B12 in its natural form. These individuals benefit from supplementation and foods fortified with vitamin B12. 

Most vitamin B12 supplements are cyanocobalamin and these are suitable for vegans and vegetarians. These groups in particular are at risk of B12 deficiency as they do not eat any animal products which are the main source of naturally occurring vitamin B12. 

Final Thoughts

There is no definitive study on which type of vitamin B12 is the most effective. There is a case for methylcobalamin being better retained in the body, but cyanocobalamin is more readily absorbed. 

While the jury is out on which B12 is the best, all are effective at improving deficiency.