Vitamin B-12 plays an immensely important role in the human body. But why do so many people have B-12 deficiencies or blood serum levels at the lower limit, despite taking supplements and/or eating "vitamin enriched" foods?
One possible answer (besides them missing the "intrinsic factor" necessary for oral uptake) is that they may simply be taking the wrong kind of B-12. Now how could that be? In order to answer this question, we need to consider what vitamin B-12 actually is.
The term "B-12" actually refers to a whole group of chemical compounds, called cobalamins. This includes:
- cyanocobalamin
- hydroxocobalamin
- adenosylcobalamin
- methylcobalamin
In the production of food supplements or food additives, cyanocobalamin is used almost exclusively. This has the very simple reason, that cyanocobalamin is easiest to synthesize (especially in pure, crystalline form) and remains durable when exposed to air. Its cheap and widely available.
The crux of the story: Unlike the other compounds, cyanocobalamin does not occur in nature. It is an invention of the chemical industry. The molecule is similar to natural cobalamins, but not identical.
It is scientifically undisputed, that only adenosylcobalamin and methylcobalamin (also referred to as "Coenzyme B-12"), are biologically active, meaning they can be utilized by the human body. The commonly held view is though, that after ingestion in the form of tablets or food additives the body can convert cyanocobalamin into the "useful" coenzyme variants.
But does it really work that way? When injected subcutaneous or intravenous, cyanocobalamin definitely appears to be accepted by the body as a replacement. It has been used that way to treat the consequences of acute B-12 deficiency for decades after all, with clearly visible effects. The vast majority of people get their vitamins from food or supplements though. And when it comes to oral intake, the story might be a completely different one.
One of the special risk groups in terms of vitamin B-12 deficiency are vegans. Natural cobalamin is bacterial in origin. Sufficient quantities for humans are only found in animal foods. There are no plant sources of B-12 (although unwashed vegetables/salads do provide miniscule amounts due to the bacteria on their surface).
This fact is actually pretty well known among those groups, who for ethical reasons make the decision to ban animal products and food from their lives. Because a B-12 deficiency can have very serious consequences, especially in the form of neurodegenerative disorders and severe aberrations in children or adolescents, many of them have their blood serum levels monitored regularly. A measure which, by the way, should be highly recommended for everyone, not only because it provides us with important data on nutritional health and the efficiency of supplementation.
Now, if you ask for experiences with cyanocobalamin within the self monitoring part of the vegan community, you get to hear the same story over and over again. Vegans are acutely aware that their blood values are, despite regular intake of "fortified food" or food supplements, at the bottom of the recommended range or even below it. And that even though sometimes daily dosages are taken, which exceed the necessary daily intake by as much as 40,000%!
Significant changes in blood serum levels and improvements of sometimes already recognizable symptoms of B-12 deficiency typically only seem to occur, when they either switch to injections, or change their supplements from those containing cyanocobalamin to methylcobalamin or adenosylcobalamin. It is the latter fact, supported by a host of anecdotal evidence (but sadly missing proper research yet), which is strongly pointing towards the possibility, that cyanocobalamin might be unsuitable for oral supplementation/therapy.
Supplements based on adenosylcobalamin and especially methylcobalamin are only slightly more expensive, but can unfortunately be hard to find in local trade or in pharmacies (while cyanocobalamin is touted at every turn).
The impact of changing ones source of B-12, both in terms of physical feeling, as well as in the measurable influence on B-12 blood serum levels, is regularly reported with the utmost enthusiasm. In some cases, changing the oral intake of cyanocobalamin to methylcobalamin caused the measured blood level to raise by as much as five times, within one year.
These reports are, to a certain degree, supported by a study on elderly people, who where given food fortified with cyanocobalamin. The usual dosages (as they can also be found in breakfast cereals and the like) led to no observable change in blood chemistry. Only after taking comparatively astronomical amounts, slight raises of blood serum B-12 were reported, but not nearly comparable to the above-mentioned results with methylcobalamin. Unfortunately, the researchers in that study failed to compare cyanocobalamin to other variants.
However, in this special case the lack of hard scientific evidence does not have to be problematic. It is pretty easy, to just watch ones own reaction in a self-experiment. Any general physician can help to monitor ones blood-serum level of B-12 as part of a regular health check-up. A regularly updated health diary may help to take an objective view on your personal energy level and general "well beeing". According to the current state of science, it is also not possible to overdose on vitamin B-12 by taking it orally.
Meaning there is absolutely no reason not to try and simply take methylcobalamin or adenosylcobalamin as a supplement and see what it does for you.