Battle of B12: Methylcobalamin vs. Cyanocobalamin

Chemical Structure of CobalaminFollowing our massive discussion on B12 injections, many people were asking the classic ‘methylcobalamin vs cyanocobalmin’ kind of questions. I’ve contacted Aqsa to make a comprehensive comparison of the two, and the result is right here.

For those of you not aware, Methylcobalamin and Cyanocobalamin are two different forms of Vitamin B12. Let’s dive right in and have a look at them separately. I believe it will answer everything you want to know.


This is one of the two forms of B12 found and used in the human body (the other form being adenosylcobalamin). That means that even when you take other forms of B12 (such as cyanocobalamin), they will have to be converted to one of these forms so that the body can use the B12 effectively for the chemical reactions that require the presence of this vitamin.

Chemically, methylcobalamin (also mecobalamin, MeCbl, or MeB12) contains a methyl group attached to the cobalamin (or B12). Since it’s already one of the two forms that your body uses, there is no further conversion required and it can be used as soon as it is administered.


As its name implies, this form of B12 contains cyanide attached to the B12. Yes, cyanide is the poison you commonly hear about. However, the amount of cyanide released from this form is so small that its effect on a normal healthy individual’s body is negligible. That means that the amount of cyanide present in this form is not significant from a toxicological point of view.

Since cyanocobalamin is not one of the forms used by the human body, it has to be converted to either methylcobalamin or adenosylcobalamin for effective use of the administered Vitamin B12.

Methylcobalamin vs. Cyanocobalamin

Both methylcobalami and cyanocobalamin are forms of B12. The latter is eventually converted to the former so why do we have to compare them?

First, the effects of these two forms on the human body are not the same (explained later). These two forms are chemically different and therefore behave differently.

Cyanocobalamin is safe for use in individuals who are otherwise healthy but its use is questionable in people who smoke, those who have excessive nervous system damage due to B12 deficiency, etc. Therefore, the comparison between these two can help us decide which one is better for which situation.

A lot of sources claim that cyanocobalamin is toxic for your body – that’s obviously bad news for those who use this common form of B12. Most pharmaceutical companies sell this form and therefore, its usage is much more common.

Methylcobalamin is expensive and therefore, most people would prefer the cheaper alternative cyanocobalamin. We’ll discuss why that might not be a good choice for you.

Without further ado, let’s get down to the actual discussion – Methylcobalamin versus Cyanocobalamin.

From a ‘chemical’ point of view:

  • Methylcobalamin occurs naturally whereas cyanocobalamin is a synthetic source of B12 – it is not made by animals, bacteria, etc.
  • Methylcobalamin is one of the forms of B12 used by your body whereas cyanocobalamin has to be converted to either methylcobalamin or adenosylcobalamin so that your body can use the B12 in it.
  • Cyanocobalamin contains the toxic substance cyanide. Although the amount of cyanide present in it is not harmful for healthy people, it has to be used with caution in people who smoke or have other problems due to which their body cannot eliminate cyanide (see below).
  • Cyanocobalamin is made by a chemical reaction and therefore it’s cheap for pharmaceutical companies to make this form of B12. Methylcobalamin cannot be made by such a reaction and has to be obtained from bacteria and therefore, it is much more expensive to procure this form of B12.
  • Once these two enter your body, they behave very differently. Methylcobalamin is used up as it is and no additional substances are required to convert it into a usable form. Cyanocobalamin, on the other hand, needs removal of its cyanide group which is done by using up glutathione and methyl groups in your body.

Glutathione is a substance that helps lower homocysteine (which contributes to heart disease when present in high amounts. For more info, see below), reduces damage caused by oxidative radicals, etc. So in a nutshell, cyanocobalamin makes your body do more work at the biochemical level and depletes your glutathione and methyl stores – both of which are required in crucial processes within your body.

Methylcobalamin, in comparison generates SAMe (S-adenosyl methionine) which is the most important methyl donor in your body providing the much needed methyl groups for crucial chemical reactions to help maintain your health.

At this point you might be thinking something like ‘hey, that’s a lot of medical mumbo jumbo – I still don’t know which form is better for me and why!’ Well let’s apply the above knowledge to your body and see which form does what. So from a medical point of view, here’s what you need to know.

From a medical point of view:

  • Methylcobalamin, according to latest research, has been proven to be the more easily absorbable and more bioactive form of B12. Moreover, it stays within your body for a longer period of time (meaning that it doesn’t get flushed out of your system as soon as cyanobalamin does due to which a single dose lasts longer than that of cyanocobalamin).
  • Methylcobalamin lowers homocysteine levels whereas cyanocobalamin does not. High levels of homocysteine cause heart disease and atherosclerosis. It is best to use folic acid in conjunction with methylcobalamin to reduce homocysteine levels.
  • Although methylcobalamin is used mainly in the liver, brain and nervous system; it is extremely useful for maintaining nervous system health. So if this system is not functioning well, methylcobalamin should be the preferred form of supplementation. Your vision has a lot to do with your nervous system since the optic nerve (the nerve within your eye which is involved in processing all sorts of visual information) is a part of it. So problems related to vision as a result of B12 deficiency benefit from methylcobalamin.
  • Methylcobalamin has been scientifically proven to help modulate your sleep-wake cycle. The exact mechanism is not completely understood but it has been suggested that this form of B12 could modulate the synthesis of melatonin, a hormone involved in regulation of your sleep-wake cycle.
    • It has been suggested that 3000 mcg of methylcobalamin taken daily along with exposure to bright light in the morning can help fix a messed up sleeping schedule. So for those of you who feel that they can’t sleep before the clock hits 3 in the morning, methylcobalamin might just be the ultimate ‘cure!’
  • Those who take methylcobalamin for supplementation of B12 report that they need less sleep as compared to those who take the cyanocobalamin form. In addition, the former group is more likely to wake up more refreshed and have more energy during the peak hours of the day probably due to a higher body temperature at this time. All these effects are not noticeable with the use of cyanocobalamin. Individuals who have blood types A or AB have lower body temperatures and therefore, could benefit even more with methylcobalamin than those with other blood groups.
  • Those who smoke or have liver problems should not be given cyanocobalamin because they cannot effectively eliminate the cyanide from their body.
  • Cyanocobalamin is usually given only intramuscularly whereas methylcobalamin can be given intramuscularly, intravenously and intra-articularly (within the joints) due to the fact that it is the more bioactive form.
  • Methylcobalamin is slightly more painful when injected as compared to cyanocobalamin.
  • Latest research proves that methylcobalamin, in high doses, can help regenerate nerves and can be useful in the treatment of peripheral neuropathies. Patients with multiple sclerosis did not improve with respect to their motor symptoms but methylcobalamin did seem to improve their visual and auditory symptoms.

Those with Alzheimer’s disease noticed an improvement in memory and intellectual functions when given this form of B12. It has been proven to have a beneficial effect on patients with Bell’s palsy (facial nerve paralysis), amytropic lateral sclerosis, parkinson’s disease, etc.

Much more research still needs to be done till doctors can finally agree upon the exact dose and duration of therapy required to treat patients with these diseases but methylcobalamin (and NOT cyanocobalamin) has at least been proven to have a positive effect in all the above mentioned conditions.

The Final Verdict: Cyanocobalamin vs. Methylcobalamin

After having read the above discussion, the choice is up to you. Which form do YOU prefer? If it were up to me, I’d say we should stop the production of cyanocobalamin altogether and make efforts to lower the cost of methylcobalamin so that it can easily be used by everyone. But hey, thing’s aren’t always that simple now, are they?

Methylcobalamin B12 Shots

If you’re looking to buy B12 shots, TrimNutrition’s Methylcobalamin are very very recommended. They are very reasonably priced and are produced in the U.S.A. They also sell Cyanocobalamin shots. I’ve personally checked their product and the quality is just fabulous.


Written by Dr. Aqsa Ghazanfar, main author of ‘The B12 Deficiency Survival Handbook’.


  1. Open says

    , 5000mcg, 60 Lozenges (Health and Beauty) I have tried other sublingual B-12 s (MRM’s) and never nectiod much but this one had really good results for me. Most sublingual B-12 s are cherry and this tastes pretty much like the rest. It also doesn’t dissolve all that well but I find that also with other sublinguals. The methylcobalamin B12 is the only one that crosses the blood brain barrier. I think the 5000 mcg is the highest dosage made in one sublingual. I just had a huge relapse of my Chronic Fatigue Syndrome. I searched for something that might help my debilitating brain fog. I got this out of desperation. I actually tried to cancel my order but I’m glad I didn’t. I really nectiod the results on the 2nd day. I take on as soon as I wake up and my brain fog is about 90% gone. I also have some extra energy which I really need in the morning. I have not tried one in the afternoon yet but I’m going to. I think we all react differently to things and I’m really happy about my results with this. I think if you want to try a B-12 this is a good one to start with. I got it on Subscribe and Save and will keep it that way. The price is too good.

    • kim priemer says

      Can you be more specific about the 5000mcg B12 lozenges? Name brand and where to buy? My daughter is very ill with B12 deficiency. Only shots available are cyanocobalamin which she just started. My daughter won’t take the cherry sublinguals. She is too weak to go out. Hospital would not admit her. It is an effort for her to breathe.

  2. jennifer says

    Very informative article. My questions :
    When exactly was the article written?
    Is it known as to how much methylcobalamin the body can absorb at one time?
    Should methylcobalamin sublingual supplements be taken on an empty stomach, or with meals?

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