Last night I watched an episode on NBC's The Doctors. If you don't know the show they have four doctors with different specialties discussing and educating the audience on popular health care topics. A great idea and my first time watching it.
One of the topics for discussion was whether vitamin B12 injections have any effect. The answer from the panel was a quick, "No, the energy increase the person is experiencing is simply a placebo effect, there is no reason somebody would be low in vitamin B12 they should be getting it from their diet."
I was seriously surprised at the oversimplification and misinformation as this comment is basically 100% false and misleading. So in an effort to create a sane stream of health information, here's the deal with vitamin B12.
Vitamin B12 is important for nerve and blood health among a host of crucial biochemistry. Thebest dietary sources are from animal products such as meat (especially liver), fish, eggs and dairy. As as side note, no plant foods can be relied on as a sole source of vitamin B12, If you are vegan I strongly suggest supplementing. I say sole source because you would have to eat several pounds of specific plants a day to get close to the daily requirement. There are bacteria in the colon which are capable of producing B12, but their location makes it difficult for absorption (hence why many vegetarian animals eat their own feces such as rabbits etc). The fermented soy, spirulina, seaweed, algae and nori products don't actually contain B12, but an inactive analogue which does not serve the needs of an omnivore's physiology nor lower MMA levels (test to determine biological activity of B12). Of course artificially fortified foods remain an option for those choosing this path.
As a side note, human feces is loaded with B12 due to these bacteria (I'm sorry, put your food away, besides you shouldn't be surfing the web and eating anyway). Researchers found a group of Iranian vegans who showed no signs of B12 deficiency - it was discovered that the reason behind this was that they at vegetables fertilized with, you guessed it, human feces and then did not sufficiently wash the produce. I suppose that this remains a viable alternative (no please, I'm only joking). Anyhow, I digress.
The body has the capacity to store a few years worth of vitamin B12 (mostly in the liver, which is why Pâté is such a good source of B12 - bon appetit). This is probably why the panel made the comment about the vitamin B12 shot having no effect on the body as in theory it should all be there.
It is generally not the lack of B12 in our diet that leads to a functional decrease in B12 levels, it is the assimilation. Vitamin B12 has a very complex absorption process, here are a few details.
B12 functional deficiency is quite common especially because high stress depletes this vitamin. To get back to the point of this article and the misinformation from NBC's "The Doctors" - B12 shots CAN make an enormous impact for someone who has had a long term deficiency or someone who has problems with absorption. The shot is not the long term solution however, healing the G.I. tract and ensuring all the mechanisms for absorption are intact is the long term solution. In the meantime it can provide a drastic improvement in energy and mental function. The idea with the shot is to bypass all those steps needed for absorption from the diet and simply inject directly into the tissue. The wise approach would be to use these in the interim and get down to business and fix the actual problem.