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Page moved to Talk:Vitamin B12. But there may be some cyanocobalamin-specific related issues still to treat here, so I've left it as a TALK page, not a simple redirect.

SBHarris 06:52, 3 December 2007 (UTC)[reply]

B12 the band[edit]

I have no objection to it being a dab/direct in B12 pages, but putting it in here in cyanocobalamin, is just too much. I'm taking it out. SBHarris 04:06, 4 December 2007 (UTC)[reply]

There's actually a template that is normally used for this purpose. The reason is that B12 redirects here, and it might not be what people expected (for example, when someone links to the redirect thinking about the band, or someone just types B12 in the "Go" box). The template is {{redirect}}, and results in
I think the template should be added. --Itub (talk) 08:26, 9 December 2007 (UTC)[reply]
I've changed B12 into a redirect to vitamin B12, which seems to solve the issue. --Itub (talk) 10:16, 9 December 2007 (UTC)[reply]

Cyanocobalamin Toxic[edit]

I've moved this section here until it can be verified and referenced:

It has been found to produce cyanide in your system in the formation of it into methylcobalamin, which is used by the body. This cyanide can react with potassium to form potassium cyanide (KCN) which is highly toxic. So one should use good forms of Vitamin like methylcobalamin, which is found naturally in nature, and can be readily used by your body. :) This was written by a college student very much into food, and in no way can back up these claims. But, scientists have written on the subject, and i hope someone can do some research and correct me if I am wrong in any way.

-- Ed (Edgar181) 12:33, 7 January 2008 (UTC)[reply]

In response to the original query, is it reasonable to expect potassium cyanide to remain undissociated in the body? Does the potassium make any difference at all? --Rifleman 82 (talk) 13:57, 7 January 2008 (UTC)[reply]
No, there will be no specific cation associated with cyanide in a biological environment, but the toxicity of cyanide is independent of the cation associated with it anyway. The important issue here is: Does cyanocobalamin generate any free cyanide under biological conditions; and if so, is the amount generated enough to have negative health consequences? Any statement we make is this article relative to this question needs to have a reliable source. -- Ed (Edgar181) 14:14, 7 January 2008 (UTC)[reply]

This article might shed some light. (I'll read it when I have more time): PMID 7090966. --Rifleman 82 (talk) 14:20, 7 January 2008 (UTC)[reply]

There seem to be some issues with the toxicity section again, as well as some other edits in the article. There are numerous issues with respect to POV, tone, and unsubstantiated health claims. It definitely needs a closer look. Things like: "Unfortunately B12 cyanocobalamin is added to fortify" and "Cyanocobalamin is possibly a silent killer of life, since it is inactive and might occupy the place of vitamin B12 in enzymes." were added in a single large edit. I suspect there are other issues lurking in the article. MachinaLabs (talk) 16:18, 10 March 2015 (UTC)[reply]
Cyanocobalamin is the inactive form of B12 that does not occur in nature and should not occur in enzymes. The conversion of cyanocobalamin into the bioactive forms of B12 is very limited. Fortification of human and animal food with the inactive cyanocobalamin is indeed unfortunate, since people have no choice and possibly the B12 cofactor in enzymes is occupied by the inactive cyanocobalamin. Nowadays the bioactive forms of B12 methylcobalamin and adenosylcobalamin are available and in that case it is indeed rather unfortunate to fortify human and animal food with the inactive cyanocobalamin. A more neutral approach is desirable where people have the free choice to have only bioactive forms of B12 in their diet. Wimbartx (talk) 08:28, 11 March 2015 (UTC)[reply]

Stuff and Nonsense[edit]

It is safe to pitch this into the dust bin. Potassium cyanide is NOT a concern. In fact, potassium cyanide isn't the concern at all, and those who observed that the potassium moiety is irrelevant are quite correct. KCN salt doesn't exist in the body: KCN is only present in solution, and it is fully ionized. Ditto for NaCN, LiCN, etc. HCN is a weak acid so it remains in equilibrium and a problem--the cell membrane is permeable to HCN.
There is no such thing a potassium reacting with cyanide. The moment KCN is dissolved becomes K+ and CN-. It is the CN- that is toxic. Unless someone has nabbed your liver & kidneys, the human body is quite capable of converting excess cyanide into thiocyanate and other such compounds. Happens every day. The trivial amounts of CN in cyanocobalamin used as a vitamin B12 source are not concerning.
There is one case where the CN-cobalamin v. OH-cobalmin makes a difference: treatment of cyanide poisoning. Large doses (much, much larger than is needed for vitamin use) of OH-cobalamin can be used to treat CN poisoning, as it combines with CN-. The body then can eliminate the excess cyanide via the usual Rhodanese pathway. (talk) 22:25, 24 January 2010 (UTC)KC, MD[reply]

False analogy, toxicity and negative interference claims[edit]

  1. The analogy to CO is false, since the body converts cyanocbl into mehthylcbl with no problems. It is not as if the cyanocbl "occupies the place" of active forms of B12 and hence interferes negatively with them.
  2. The released cyanide after the conversion is of no concern for most people/animals (the exception are people with kidney problems). Amounts of cyanide ingested in even high amounts of B12 suplements is biologically insignificant and less than consumed daily from natural foods such as fruit, seeds or vegetables.
  3. Cyanocobalamin supplements have been consistently shown to improve B12 status in people with deficiency. See eg. section 7. Prevention and Treatment of B12 deficiency here: [1]

I suggest to completely rewrite the Criticisms of Cyanocobalamin as a B12 supplement section along the lines of the following article: [2]

The safety of cyanocobalamin has raised concerns due to the fact that cyanide is a component of cyanocobalamin, and the cyanide molecule is removed from cyanocobalamin when used by the body's cells. Cyanide is also found in many fruits and vegetables and so humans are always ingesting small amounts of cyanide, and like in most fruits and vegetables, the amount of cyanide in cyanocobalamin is considered to be physiologically insignificant.
According to the European Food Safety Authority, "Data of from a Norwegian dietary survey show that the average and high (97.5th percentile) daily intake of [cyanide] among consumers amounts to respectively 95 and 372 micrograms/person or 1.4 and 5.4 micrograms/kg bw/day (7)." The amount of cyanide in a 1,000 microgram cyanocobalamin tablet is 20 micrograms.

--Compostus (talk) 09:07, 29 August 2015 (UTC)[reply]

This is not acceptable because some people have a cyanide metabolism problem which renders this contaminated cobalamin an antivitamin to them. I believe this disorder is currently classified as Leber's hereditary optic atrophy. (talk) 23:34, 26 August 2022 (UTC)[reply]

Ordering ingredients by weight[edit]

"This fact has caused some people (usually from reading labels on packages and vitamin supplements, in which vitamin B-12 is almost always listed last, since ingredients by law are listed in order of weight percentage)"

I know that US law mandates that food list ingredients in order of weight, do other countries have this law? —Preceding unsigned comment added by (talk) 13:01, 13 February 2009 (UTC)[reply]

Animal Protein Factor[edit]

Animal Protein Factor redirects here but there's no explaination or mention of Animal Protein Factor in this article Nil Einne (talk) 09:52, 2 November 2010 (UTC)[reply]

This article in desperate need of clean-up from bad edits[edit]


  • 1. the cyanide is covalently bound to the cobalamin moeity. Cobalticyanide has a high formation constant. One cyanide treatment (as effective as hydroxy-B12) is Cobalt EDTA complex. Sodium Ferrocyanide is added to Table Salt as an "anti caking agent" and withstands stomach acid. Enzymes are required to remove the cyanide to form the active enzyme co-factor. The human body stores B12 as Cyanocobalamin because it isn't as likely to react with other body molecules like Nitric Oxide.
  • 2. yes cyanide exists in the human body normally either through ingested food (almonds, cherries, raspberries, cassava root flour, drinking water, et al) or metabolism (oxidation of thiocyanate by salivary peroxidases; We used to think Nitrites and Nitric Oxide were toxic and cancer causing until it was found to be a neurotransmitter responsible for heart function and erection.
  • 3. B12 and Rhodanese can oxidize cyanide to thiocyanate at about one gram of cyanide per hour when activated. B12 RDA is 2-3 microgram.
  • 4. I did environmental testing at an industrial test lab for five years. We did parts per billion testing for air contamination and never had a positive test for hydrogen cyanide from an activated charcoal blank. There is no reference for that statement, that hydroxy-B12 acquires a cyanide molecule while being filtered by activated charcoal, in this wiki article.
  • 5. 4 gm of hydroxy-B12 and 8 gm of Sodium Thiosulfate was one cyanide antidote. The point of action of Cyanide is cytochrome oxidase in the mitochondria binding to the oxidized iron; Sodium Nitrite is often part of the antidote, oxidizing hemoglobin to methemoglobin which binds the cyanide before it reaches the cellular level.
  • 6. a contestant on a radio show water drinking contest died after drinking 4 gallons of water at one sitting, although the LD50 was supposed to be 8 gallons. The Thiocyanate dosage for sickle cell anemia is 1 to 2.5 grams.

Shjacks45 (talk) 07:56, 11 September 2011 (UTC)[reply]

The body does NOT store B12 normally in cyanocobalamin form (rather, most is in ado-B12 form). Yes, the CN in cyanocobalamin does come from activated charcoal, and B12 from bacteria is hydroxocobalamin.[3]. This IS a reference. The idea that the body stores B12 as cyanocobalamin so it won't react with NO is nonsense. If hydroxo-B12 reacted with NO, a large dose of this intravenously would raise blood pressure by scavenging NO, and it does not. A normal dose of 4 gm hydroxocobalamin for cyanide poisoning is 1000 times the total body store of B12. Finally, if you never got a cyanide test off your activated charcoal, you obviously weren't using something as cyanide-binding as cobalt (yes, other forms of cobalt are active, too). SBHarris 06:43, 12 September 2011 (UTC)[reply]

B12 is the precursor to B12?[edit]

I think I'm missing something. At present the into of the article states "Vitamin B12 is the name for a whole class of precursors to vitamin B12", and my brain is now stuck in an infinite loop. I expect that this statement is based on something accurate, but at present it seems to be a confusing, non-helpful way to say it. I hope someone with more knowledge that me can clarify. --Keithonearth (talk) 19:50, 3 March 2012 (UTC)[reply]

See vitamer. B12 is the name for any of the class of chemicals that has the activity of B12 in the body (cures symptoms of B12 deficiency). A precursor to B12 will itself be B12. B12 is not a "thing" but class of things defined by what they do. SBHarris 01:55, 4 March 2012 (UTC)[reply]
I think the intro would benefit with making that more clear. Do you think it is clear as it is now written? --Keithonearth (talk) 18:19, 4 March 2012 (UTC)[reply]
Hard for me to tell since I've rewritten it so much at this point. Why don't you reread and tell me what it still lacks? SBHarris 21:53, 4 March 2012 (UTC)[reply]

The molecule-picture[edit]

The molecular structure is mad in another program than the structure for Methylcobalamin and Hydroxocobalamin, which makes the hard to compare. I know it's only a question of the part that binds Co, but it would still be easier to conclude the rest of the structure is the same, if it was drawn in the same fashion. Can anyone do it in an easy way?

OxygenBlue (talk) 07:10, 24 July 2012 (UTC)[reply]

Mention of Cyanocobalamin Reductase?[edit]

Should there be a reference on this page to the enzyme Cyanocobalamin reductase? Looking this up on google, I ran across the enzyme article. (Safari auto-spell-guess-auto-search is nice..) I don't know enough about it (obviously) to know where (or if) it is a major contributor to Cyano-B12 metabolism in humans or bacteria. — Preceding unsigned comment added by Jimw338 (talkcontribs) 19:16, 6 September 2012 (UTC)[reply]

Cyanocobalamin Injections, aluminum toxicity?[edit]

I come across this on several medical/drug info sites, take for example the Drug label from American Regent, Inc. on

  • This product contains aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired.
  • Premature neonates are particularly at risk because their kidneys are immature, and they require large amounts of calcium and phosphate solutions, which contain aluminum.

However, apart from Warning sections, I haven't found any mention of aluminum. It's not listed under the active or inactive ingredients.

  • Each mL contains: Cyanocobalamin 1000 mcg, Sodium Chloride 0.9%, Benzyl Alcohol 1.5%, Water for Injection q.s. pH (range 4.5 – 7.0) adjusted with Hydrochloric Acid and/or Sodium Hydroxide.

So where does it come from, some impurity from the production process? And in what form is it? Ssscienccce (talk) 08:34, 20 November 2012 (UTC)[reply]

The Vitamin B12 Deficiency section is more about the metabolism[edit]

so I'll rename it to Vitamin B12 metabolism, and most of it should move to the Vitamin B12 article. - Rod57 (talk) 13:58, 17 August 2015 (UTC)[reply]

"Criticisms of Cyanocobalamin as a B12 supplement" poorly written and sourced[edit]

The "Criticisms of Cyanocobalamin as a B12 supplement" section of this article is very poorly written, repetitive, and lacking of sources. I suggest a major cleanup or deletion of that section. PStrait (talk) 03:05, 9 January 2016 (UTC)[reply]

I deleted the entire section. As a person with a doctorate in nutritional biochemistry from MIT, I agree with the opinion above. The content lacked references, and those provided did not support the content. Cyanocobalamin is widely accepted as a synthetic, supplement-appropriate form of vitamin B12 - functional and safe.David notMD (talk) 02:49, 28 February 2016 (UTC)[reply]

More clean-up[edit]

I have been attempting to clean up style and remove text either redundant or contentious. Next step to consider is severely cutting the entire B12 metabolism section, as this is covered in the vitamin B12 entry. THIS entry on cyanocobalamin should be on that synthetic compound and not on what happens after it is converted to the physiologically active compounds.David notMD (talk) 12:57, 1 March 2016 (UTC)[reply]

B12 production companies[edit]

At the end of the 'Production' subsection, we have this line:

"The total world production of vitamin B12, by four companies (the French Sanofi-Aventis and three Chinese companies) in 2008 was 35 tonnes."

Is there a reason why only the French company is mentioned and not the three Chinese companies? I think all four companies should be mentioned, else the whole of the brackets should be removed. The cited article is paywalled, so I'm unsure if the original source mentions all four companies. WikidKev (talk) 23:06, 10 January 2024 (UTC)[reply]