[Outofstyle]

It depends on the source of the vitamin.... For example, vitamin A can cause a person to overdose if you get too much, but some foods provide vitamin A in the form of beta carotene, which the body has to convert the beta carotene into vitamin A, and your body will not convert it if you do not need it, thus you cannot overdose on beta carotene even though it is a source of Vitamin A.

I don't know if this is the same for B12 in PM, but I have not heard of anyone having any issues..