The most effective form of vitamin B12 is methylcobalamin. The body uses methylcobalamin directly, so it’s very easily absorbed. The same goes for dibencozide, which the body uses for muscle development among other things. Canadians do not get dibencozide – they can only get it from the U.S. Cyanocobalamin is crap – don’t use it. Smokers should use methylcobalamin, as it will bond to the cyanide in the body and will be excreted though urine.
Cyanide poisoning is not a nice way to go. Essentially it’s open-air suffocation. Cyanide ions in the body interact with an enzyme called cytochrome oxidase. This enzyme works with hemoglobin in the blood. It preferentially picks up cyanide when it should be picking up oxygen, meaning the body slowly dies for lack of “air.”
There’s a classic joke about how to get intoxicated at hospitals by claiming you drank methanol to get an IV with an ethanol solution. It’s not that methanol will kill you or make you blind… The problem is that the liver enzyme alcohol dehydrogenase turn methanol into formaldehyde (or methyl aldehyde). Ethanol binds to the same enzyme to inhibit the production of formaldehyde.