Chemical Forms of Vitamin B12: Methylcobalamin and Cyanocobalamin

Chemical Forms of Vitamin B12: Methylcobalamin and Cyanocobalamin

Vitamin B12 (Methylcobalamin and Cyanocobalamin) is one of the vitamins that belongs to the B complex. It is available in four different chemical forms in nature: cyanocobalamin, methycobalamin, hydroxocobalamin, and adenosylcobalamin.

There is a huge population of bacteria (Bacteroides and Bifidobacterium genus) in the intestinal tract that can produce B12. However, it is mainly located in the large intestine (specifically the colon). Consequently, this lowers its efficiency since the absorption of B12 takes place before, in the duodenum.

When it comes to nutrition, the natural sources of this compound come from the animal kingdom. In fact, the best one is lamb liver, followed by chicken and beef liver, beef and lamb kidney. As well as oysters and other mollusks without shell such as octopus, oily fish (sardines, trout, tuna, and salmon), eggs and dairy products (specially cheese). The list would not be complete without mentioning the vegetable kingdom and whole cereals enriched with vitamin B12.

Before diving into the differences between cyanocobalamin and methylcobalamin, we will explain the function of this vitamin in the organism. It goes from the functioning of the bone marrow and the formation of red cells, to the functioning of the gastrointestinal and nervous system.

The function of cobalamin

Inside the cells, cobalamin is an indispensable element in strategic processes such as: the synthesis of the amino acid methionine, the use of essential fatty acids to produce energy (Krebs cycle), the synthesis of acetylcholine, and the DNA replication.

From all of its forms, methylcobalamin is the only one that affects the central nervous system, the brain basically. In order to obtain it, the liver carries out a biochemical transformation. Then, cyanocobalamin will transform into 5-deoxyadenosyl cobalamin and methylcobalamin. Then, it will provide all its benefits to the organs that need it, such as the brain. In fact, if this process is interrupted by pathological disorders or a congenital deficiency, it would end up in a B12 deficiency. Consequently, the brain and other organs such as the bone marrow would be seriously compromised.

However, the bioavailability of methylcobalamin does not result in a higher biological activity in the tissues or organs. This is what truly triggers or inhibits a vitamin deficiency. In any case, we still need to conduct more research in order to reach a conclusion.

Once transformed, vitamin B12 has to cross the intestinal barrier in order to enter the bloodstream. In order to achieve this, it needs the support of an intrinsic factor (a glycoprotein) produced by specialized cells from the stomach walls. A diet rich in vitamin B12 or even supplementation would not prevent deficiency of this vitamin without this factor. All of this with the symptoms it would involved, mainly neurological dysfunctions and pernicious anemia.

The scientific community considers that methylcobalamin is more efficient and bioavailable than cyanocobalamin.

Properties of Methylcobalamin

At this point, the ability of methylcobalamin to prevent disorders of the nervous system deserves a special mention. It protects the myelin sheaths, which are layers of phospholipids and proteins that surround the neurons. Moreover, they enable a fast transmission of electric signals between them.

This vitamin is strictly related to beneficial micro-organisms for our health. This is due to the fact that all the vitamin that reaches our organism comes from a process of bacterial synthesis. Therefore, we need specific bacteria in order to produce dietary supplements in a laboratory. On the other hand, animals that have been reared intensively have an interesting B12 content. This is mainly due to the extra vitamin-mineral regulators from their fodder, whose bacteria are carefully studied in order to obtain a successful breeding. When it comes to animals reared in pastures, their high vitamin B12 content comes from the bacteria that live in the soil.

Vitamin B12 for sportspeople

Vitamin B12 as cyanocobalamin is regarded as a very safe compound overall. But when it comes to cobalamin, there is not enough data to assess its toxicity with certainty. However, some studies conclude that up to 6000 micrograms daily would be safe. Although 300-400 micro-grams are already extremely efficient. Evidently, there is more scientific evidence for cyanocobalamin than for methylcobalamin regarding its safety/toxicity and its bio-activity. This is the reason why it is the most common formula in dietary supplementation.

The amino acid homocysteine can mark a drop of vitamin B12 levels, specially methylcobalamin. In fact, its excessive amounts in blood mean that there is a low methylcobalamin level in the organism. This could be the beginning of a deficiency. A way to reduce the homocysteine levels is using folic acid supplementation. However, its effects are enhanced when we combine it with methylcobalamin.

How does vitamin B12 support a better rest?

It seems that methylcobalamin performs an important task in the synthesis of melatonin. This is a hormone released by the epiphysis or pineal gland in order to regulate our “biological clock” or circadian rhythm. The information available reveals that methylcobalamin could regulate the release of melatonin.

Due to this, people have been requesting a supplement with methylcobalamin to improve the quality of sleep. According to this, a high dose of methylcobalamin (around 3000 micro-grams a day) and sunbathing in the morning light could be an efficient way fixing this biological clock if it breaks.

What should we take into account when choosing a Vitamin B12 supplement?

Chemical form

If we plan to use supplementation for maintenance purposes, cyanocobalamin would be better for the following reasons:

  • As we previously mentioned, it has more support from the research.
  • Moreover, it can be stored for a longer period of time due to its stability against environmental factors.
  • It is more affordable, a valuable aspect if the treatment is going to last for a while.
  • It would not be reckless to use it without medical supervision, since there is plenty of information about it.

However, there are situations when methylcobalamin will be better. For example, if our aim is to treat a vitamin B12 deficiency in chronic smokers or patients with renal or hepatic deficiency.

Dose for both forms of vitamin B12

An interesting measure is to adopt a referential intake per week, by selecting a supplement whose units contain 2000 mcg for a single intake, or 1000 mcg for two. An important detail is that this form is more affordable, since it reduces the price per tablet.

However, if you still want to choose a daily supplementation routine, which also entails a greater risk of an insufficient absorption, the supplement that is chosen should have between 25 and 100 micro-grams. This amount surpasses greatly the DRI (Daily Recommended Intake) established by the European institution which is in charge of nutritional safety. This amount is only of 4 mcg per day, but this number is for a distributed consumption pattern, whose absorption efficiency is inversely proportional to the dose, which is the reason why the dose should not be proportionate when we compare the weekly supplementation to the daily one.

If we need to meet the requirements of a vegetarian person, we should make sure that the supplement has enough vitamin B12, since plenty of them lack the amount that these people need.

Chemistry books


Cyanocobalamin is sold in capsules, tablets, nasal gel, and injectable ampoules.

But, what is the best way to consume the vitamins?

Without any doubt, the most adequate administration is oral, since a dose of 1000 micro-grams has the same efficiency than an injection. Nevertheless, there are some people who would rather avoid using injectable ampoules in order to consume them dissolved in water.

According to the information from “Nutrition Journal”, there could be differences in the near future regarding the field of therapy. It regards methylcobalamin as a powerful agent against cancer, which would slow the growth of tumors and inducing the apoptosis or death of cancerous cells, as it has been proven in experimentation animals. According to the article, these effects were not found in trials carried out with cyanobalamin.

You can purchase vitamin B12 supplements at our HSN online store at the best price.

To sum up, even though methylcobalamin has more advantages when it comes to its absorption, it is advisable to use cyanocobalamin supplementation, since it is the most studied form. It has an immense safety threshold (even in extremely high doses). Both the Institute of Medicine from the United States, as well as the Expert Group on Vitamins and Minerals from the United Kingdom, state that methylcobalamin lacks, for the moment, enough scientific support in order to use it for long-term supplementation.

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About Alberto Ricón
Alberto Ricón
Alberto Ricón is a specialist in nutrition and food hygiene with large experience in the sector as well as being a Food Health Technician.
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