The most commonly available form of vitamin B-12 on the market is the cheap synthetic form that's actually bound to a cyanide molecule (yes, cyanide, the poison). It's called cyanocobalamin, and you'll find it in all the cheap vitamins made by pharmaceutical companies and sold at grocery stores and big box stores.
The proper form of vitamin B-12 to supplement is called methylcobalamin. This is the form that exists in nature, and it is pre-methylated, meaning it's ready for your biochemistry to put to immediate use. Methylcobalamin has several key advantages over cyanocobalamin:
* Increased absorption* Better retention in tissues* Contains no toxic cyanide* Supports production of SAMe