What Is B12 vitamin? What are B12 benefits And What's The Difference Between Cyanocobalamin vs Methylcobalamin

Updated Oct 2016:
This link is a 15min video that summarizes even more about B12 and B12 deficiency.

I've had quite a few patients ask me, "so what's the difference between all the different types of B12 and why does the cost vary so much, and why should i care?" Ive also had just as many patients tell me that they didn't know that there were different forms of B12. So I put this together to give everyone an idea of the functions of B12 and the differences between the 3 forms of B12. 

B12 Functions
B12 (cobalamin) is one of the many water soluble vitamins that your body needs for good health. B12 is needed to promote digestion; nervous system health; fatty acid metabolism, protein metabolism and folic acid metabolism as well as many enzyme reactions in the body. 

"How can I know that Im low or deficient?"
It is indicated in pernicious and macrocytic anemia. People with low stomach acid will likely absorb less because stomach acid and other factors aid in B12 absorption. It can also manifest in fatigue, cardiac problems, neurological disorders (memory loss, sensation changes, confusion, depression), orthostatic hypotension (feeling dizzy when you stand up quickly), and decreased immune function. It may also affect melatonin production leading to sleep issues. It is also indicated in people taking the oral contraceptive pill. The dosage and method of B12 administration should be discussed with your Naturopath or MD prior to starting the supplement.

Some people have genetic defects that cause them to not convert B12 into the active format effectively. This can be evaluated by genetic testing.

Testing your B12
Serum B12 (blood test) is the most common way to have your B12 levels evaluated. Since B12 is involved in so many processes in the body, I like to see the levels in the mid-high range on the blood test. 

Food sources
According to the Dieticians of Canada, the majority of B12 in your diet comes from meat sources. Therefore people who don't consume meat should consider B12 supplementation. There are currently mixed reviews about algae and its use as a B12 source in the diet. 

So now that we know what B12 does and we know its food sources, "what's the difference between all the different B12 forms?"
There are 3 main forms: Cyano, Methyl, and Hydroxy.

Cyanocobalamin
Is the synthetic form of cobalamin used in many supplements. It's popular because of its low cost and stability. It's usually found only in trace amounts in the body. Cyanocobalamin must be converted to the methylcobalamin form in order to become active in the body. Therefore it has no real function in the body other than to be broken down into an active form. When cyanocobalamin is metabolized, it dissociates leaving the cobalamin (B12) and a cyanide ion. Cyanide is a poison to humans. Due to the cyanide portion of this form of B12, it is contraindicated in smokers and people with kidney problems. It as also been mentioned to be avoided in children with autism (still being debated).

Methylcobalamin
This is the coenzyme form of B12 that is used in the metabolism of all the processes mentioned earlier. This form does not require conversion in the body and is therefore more direct in its actions as a supplement. The main difference here is that the methyl form of B12 costs more. However, now the cost difference between cyano and methyl is not so large. 

Hydroxycobalamin
Is another form of B12 that is very similar to methylcobalamin. These two forms of B12 have shown very similar methods of action, absorption efficiency and effectiveness. The difference here is that Hydroxycobalamin lasts longer in your body. It is not put into the more bioactive form of Methyl right away so your body doesn't use it all up at once. 

The debate will continue on whether to choose cyano or methyl or hydroxy. For my patients, I will always choose methyl or hydroxy forms. For me, there is no point in trying to save money in choosing cyano if I don't absolutely need to. I suppose if something happens to the world's supply of methyl and hydroxy, making them extinct, then yes, I would use cyano. However, until that day comes, I really don't see the need to do so. As for the cyanide safety debate, rather than take a chance with my patients, I would rather just go with the form that is known to not have any concerns with cyanide. It just makes sense to not take the chance with your health. As of now the research claims there is no significant risk in choosing the cyano form, but we used to say the same things about plastics (phthalates, BPA), lead paint, leaded gas, asbestos, hand washing before surgery, and the use of cocaine in coca cola.
So for the minimal difference in cost and the less risk of harm, I would go with methyl or hydroxy, it's more bioavailable and is the more natural form. 

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