When talking about vitamin B12, this is actually a generic term for a class of compounds called the Cobalamins, and indeed when one has vitamin B12 deficiency, it is more scientifically called Cobalamin Deficiency. This makes perfect sense when you understand that the various formulations of Vitamin B12 all end with the suffix Cobalamin. While there are MANY `Cobalamins`, only three are generally used as dietary supplements, namely:
Hydroxocobalamin
Cyanocobalamin
Methylcobalamin
All three types are considered `Vitamin B12`, they are NOT all the same and using the right one can be a critical decision. Cyanocobalamin is probably the most commonly used in the medical world and is often given as `B12 Shots` in a doctor's office for those with certain medical conditions. But cyanocobalamin is actually the WORST choice, despite the fact that doctors in the US are more likely to prescribe it over any other form. Not only does cyanocobalamin require a higher dosage for the same effectiveness of hydroxycobalamin, but it is Entirely Ineffective for several different conditions related to vitamin B12 deficiency. As such, it has been suggested repeatedly by several researchers, starting with Dr. AG Freeman in 1970, that cyanocobalamin should be removed from the market. While Great Britain followed through with researcher recommendations and removed the inferior product, doctors in the the United States have no such restrictions and still use cyanocobalamin routinely.
"...there [is] no condition in which it has been
claimed that cyanocobalamin was
preferable to hydroxocobalamin"
`Cyanocobalamin- a case for withdrawal: discussion paper`
While hydroxocobalamin is preferred over cyanocobalamin, another formulation called methylcobalamin is actually the BEST choice. Technically a `coenzyme` of vitamin B12, it is almost never used despite being effective, readily available, inexpensive and available in both sublingual preparations and injectable form. This is too bad because there are many people that could very well benefit from the methylcobalamin form of vitamin B12 that would NOT benefit from the other forms. Degenerative neurologic problems are where methylcobalamin shows its greatest benefits over other cobalamin preparations, and it is often one of the ONLY promising treatments for these tragic diseases. While Japan uses methylcobalamin nearly exclusively and it is the form present in prescription vitamin B12 there, the United States has virtually ignored the hundreds of studies that show the benefits this simple vitamin can bring.
"Methylcobalamin is the form found in food and
has much higher bioavailability than the form most
widely available in supplements, cyanocobalamin."
`B12 (Cobalamin)`
Not only has methylcobalamin been shown to work in neurologic diseases, it also helps with the elimination of toxic substances in the body. One of the ways that humans detoxify is through a process called 'Methylation'. Methylation is a CRITICAL function of a healthy body, but all too often we 'use up' the necessary raw materials because of our nearly constant exposure to environmental pollutants. Methylcobalamin is actually able to replenish the 'methyl' portion that is missing in methylation, while the other forms of vitamin B12 REQUIRE a methyl donor in order to be converted into a biologically active form in the blood. Therefore, people who already HAVE methylation detoxification problems, such as children with autism, can actually be made WORSE if other forms of vitamin B12 are administered!
While getting ENOUGH vitamin B12 is an important factor for maintaining general well being, getting the right KIND, in the form of methylcobalin is equally important. In fact, choosing correctly could very well mean the difference between good health and disease.
Resources:
1) http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1293728&blobtyp...
2) http://www3.interscience.wiley.com/journal/119759807/abstract
3) http://www.hormonalfitness.com/facts/HFN%209%20-%20b12%20Cobalamin.pd...
4) http://www.pnas.org/content/99/15/10072.abstract