B12 is perhaps most often thought of as an “energy booster,” but in truth, it’s unlikely to provide a significant boost in energy unless you are deficient in it.
However, B12 is crucial for a number of metabolic functions, including the production of the building blocks of your DNA, the health of your nerves and spinal cord, and the production of red blood cells,
B12 is not found in plants, so vegans (and vegetarians who don’t eat many eggs or much dairy) do need to supplement. In addition, those at risk of nutritional deficiencies due to illness are advised to discuss B12 supplementation with their doctors, or at least to monitor levels.4
The most common form of Vitamin B12 in supplements is cyanocobalamin, but you will not find that form in food; it doesn’t occur naturally in either plants or animals.
The form of B12 found in nature—and the one your body actually uses—is called methylcobalamin.
Cyanocobalamin actually has a cyanide molecule attached to it, as the name implies. It’s not enough cyanide to significantly inhibit cellular respiration, but it does require your body to neutralize it. So, the very act of taking cyanocobalamin puts your detox system to work to prevent cell damage; it’s a waste of cellular resources.
Methylcobalamin is the form of B12 that your body wants. It’s needed for the production of myelin, the fatty sheath that enables nerves to function. For this reason, low B12 levels are associated with numbness and tingling (neuropathy).*
A number of human trials have explored B12 for the treatment of neuropathy caused by diabetes or by toxic medications, with varying degrees of success.1,2,3 Methylcobalamin is also needed for something called “methylation,” which is closely tied to DNA repair, as well as the production of phosphatidylcholine,5 which makes up the membrane of every cell in our bodies.