Cyanocobalamin – The Synthetic Vitamin B12


Cyanocobalamin – The Synthetic Vitamin B12

Cyanocobalamin is a synthetic form of B12 which does not occur naturally but is often used in supplements. Is it dangerous? Who should use cyanocobalamin?

Cyanocobalamin – an Affordable Vitamin B12 Active Ingredient

Cyanocobalamin is one of the most widely available types of vitamin B12 used in supplements and and has been proven to be very successful in vitamin B12 therapy for many years. Through injections as well as oral vitamin B12 supplements, cyanocobalamin remedies many forms of vitamin B12 deficiency and is also particularly effective when treating anaemia patients.

The wide application of cyanocobalamin can be attributed above all to its advantages in the production process: no form of vitamin B12 is as easy or cheap to produce, and its chemical stability allows it a particularly long shelf life. 

Cyanocobalamin and the Discovery of Vitamin B12

Cyanocobalamin is closely intertwined with the history of vitamin B12, which was first named in 1948 when the vitamin was first successfully isolated. In 1956, the form discovered proved to be cyanocobalamin. For a long time after, it was believed that cyanocobalamin was identical to vitamin B12 and that this form must therefore be the naturally occurring form of the vitamin. It wasn’t until many years later that it was first discovered cyanocobalamin had emerged as a result of contamination in the activated carbon used in the isolation process. In addition, it was discovered cyanocobalamin doesn’t occur naturally in any notable quantities in the body, nor in foods – and actually causes absolutely no effect on its own.1

 As a result, an inadvertent and practical method had been found to stabilize this very delicate vitamin, accompanied by the discovery that hydroxocobalamin is actually the naturally occurring form of B12 as it is produced from microorganisms and that the active forms found in the body were in fact methylcobalamin and adenosylcobalamin

Cyanocobalamin – Synthetic Vitamin B12

Cyanocobalamin is therefore an artificial form of vitamin B12, which does not occur naturally – unless as a pollutant or decontaminant. As a result, our body cannot utilize it directly, as it must first be broken down into the two bioactive coenzymes methylcobalamin and adenosylcobalamin. There are four metabolic steps necessary for this process, with one part of the cyanocobalamin being converted into the B12 form hydroxocobalamin, which occurs as a preform of the coenzyme in the body, after the first step. 

Clearly, the necessary conversion constitutes a metabolic disadvantage, but under normal circumstances it functions without difficulty. A part of the cyanocobalamin consumed is excreted, however, before it can be converted – meaning the bioavailability of cyanocobalamin is comparatively not particularly ideal. 

Is Cyanocobalamin Toxic?

Cyanocobalamin is, as the name suggests, a bond of vitamin B12 and a cyano group. These are split in the body and the reaction partly causes cyanide – a substance which is commonly known as a neurotoxin. This often leads to fears that cyanocobalamin is toxic or dangerous. However, this isn’t entirely accurate, as the amount of cyanide produced is so low that only the very sensitive or those with high levels of existing cyanide exposure, for example smokers, are at genuine risk. Nevertheless, the question remains as to why such a form should be chosen, when there are more advantageous alternatives available.2

The most important thing to consider is that the three naturally active forms of vitamin B12 have specific effects and advantages against many diseases and health problems. Thus it is often recommended when taking supplements to ensure that there is a mixture of these natural forms of B12 if possible, rather than simply the synthetic active ingredient cyanocobalamin. 

Cyanocobalamin – Good Price, Relatively Ordinary Effect

Cyanocobalamin is certainly far from optimal, even in its effect. When directly compared to other active ingredients, cyanocobalamin is clearly cheaper, yet cannot compete with the other natural forms when it comes to effect.This can be seen best when viewing the absorption rate for cyanocobalamin injections (20-50%), compared with hydroxocobalamin (around 70%).Cyanocobalamin also comes off second best when compared with methylcobalamin.This comes down to the fact that methylcobalamin is a bioactive form of vitamin B12, meaning the body can use it directly. 

Despite all this, cyanocobalamin remains very effective for healthy people looking to cover their daily requirement and avoid a vitamin B12 deficiency, backed up by evidence through testing in practices. For treatment purposes, many vitamin experts would recommend working with the natural coenzyme forms, which have proven themselves to be outstanding in many different cases. When tackling diverse diseases, these natural forms have seen success which cannot be achieved through cyanocobalamin. 

Those who want to profit from the healthy benefits of the natural forms should consider whether to also use these B12 forms for standard day-to-day use.


1 Victor Herbert (1988). “Vitamin B-12: plant sources, requirements, and assay”. American Journal of Clinical Nutrition 48 (3 Suppl): 852–8. PMID 3046314
2 J.C. Linnell,D.M. Matthews,J.M. England Therapeutic Misuse of Cyanocobalamin. The Lancet – 11 November 1978 ( Vol. 312, Issue 8098, Pages 1053-1054 ) DOI: 10.1016/S0140-6736(78)92379-6
3 A.G. Freeman Cyanocobalamin – a case for withdrawal: discussion paper. J R Soc Med. Nov 1992; 85(11): 686–687.
4 Hertz, H., Kristensen, H. P. Ø. and Hoff-JØrgensen, E. (1964), Studies on Vitamin B12 Retention Comparison of Retention Following Intramuscular Injection of Cyanocobalamin and Hydroxocobalamin. Scandinavian Journal of Haematology, 1: 5–15. doi: 10.1111/j.1600-0609.1964.tb00001.x
5 Okuda K, Yashima K, Kitazaki T, Takara I. Intestinal absorption and concurrent chemical changes of methylcobalamin. J Lab Clin Med. 1973 Apr;81(4):557-67. PubMed PMID: 4696188.

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