Why are there different forms of vitamin B12?

The B12 shelf carries a quiet debate: cyanocobalamin — the cheap, stable synthetic in most multivitamins — versus methylcobalamin, the 'active' form commanding premium prices. The chemistry that settles it: the body converts cyanocobalamin to its active forms as a routine step, and trials show it raising blood levels perfectly well for most people. The active forms have genuine niches, just smaller than the marketing implies. Meanwhile the most important form on the shelf isn't oral at all — it's the injection, which exists because B12's absorption cascade breaks. This guided journey reads the labels.