Need Info regarding methylcobalamin!!!

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Melissa&Popcorn(GA)

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Hi all,

I haven't had much of a chance to review the latest protocols on the FDMB in quite awhile, but I got an email from Helen, the owner of Tanya's CRF site (http://www.felinecrf.org). She writes,

"I wanted to ask you if you guys over on FDMB have changed your opinion on the use of methylcobalamin for diabetic neuropathy in light of the recent negative studies. I'm sure you know what I'm referring to, but just in case:"

http://jama.ama-assn.org/cgi/content/short/303/16/1603
http://pubs.ama-assn.org/media/2010j/0427.dtl#3

This is quite scary - so please give me your thoughts to pass along to Helen. You can email me at jur @ eee.org. (removes spaces)

Thanks,

Melissa
 
My personal opinions are:

1. The study used a combination tablet of B-6, B-9 and B-12. They have no follow-up studies yet as to whether the damage was caused solely by the B-12, by one of the other vitamins, or the particular combination of vitamins.

2. The B-12 given to the participants is almost certainly cyanocobalamin, not methylcobalamin (I read the second article, which didn't specify whether cyano or methyl was used). As Laurie says in her article, you *really* want the methyl form; you need higher amounts of the cyano form to get the same results.

3. The participants in the study took the tablets for 36 months; from what I've seen on the board, most cats are on methyl B-12 for 3 months or less. Assuming the damage is cumulative (which is usually the case), the corresponding risk should be lower.

4. Unlike humans, diabetic neuropathy in most cats starts resolving on it's own once the cat is regulated. Methylcobalamin seems to slow the progression while the cat is unregulated, and seems to speed the healing once regulated, but is not necessary for eventual recovery.


My personal opinion (and I welcome the opinions of others):

Use of methylcobalamin should be safe for most cats. In cats with impaired kidney function, I try to would balance the current state of the kidneys against the severity of the neuropathy, and make a decision based on the risks vs. the rewards. i.e., in a cat with severely impaired kidneys and very mild neuropathy, I would opt to *not* give methylcobalamin, while in a cat with mildly impaired kidneys and very severe neuropathy, I would probably opt *to* give it.

-- Jean and her Gwyn
 
But is it all three B vits, or just one of them but they haven't isolated which one? The B9 dose in the study is more than double the tolerable upper intake level listed on wikipedia (I'm too lazy to look up other sources).
 
To further complicate the use of the Methyl form vice cyano, wiki says:

A common synthetic form of the vitamin, cyanocobalamin, does not occur in nature, but is used in many pharmaceuticals and supplements, and as a food additive, due to its stability and lower cost. In the body it is converted to the physiological forms, methylcobalamin and adenosylcobalamin, leaving behind the cyanide, albeit in minimal concentration.
 
Holy cow! By using the Methyl B12, we hopefully bypass the conversion process (and the cyanide byproduct). My understanding, as well, is that the Methyl form of B12 is water soluble, and what the body doesn't need is excreted out in the urine, thereby not accumulating in the tissues/organs.

I would still use the MB12... but will watch this for further developments.

Thanks, Melissa.
 
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