A B12 measurement is almost a random number. It does not correspond well with functional B12 status and should not be believed. I and others on this forum can give you proper peer-reviewed medical references that confirm this. If there is any possibility at all that you have a B12 deficiency then you really should start taking a supplement, after, if possible, having your homocysteine and methylmalonic acid measured. These measurements (particularly methylmalonic acid) are much more more sensitive and specific for functional B12 deficiency than a blood B12 measurement. (I had to spell methylmalonic acid for my GP when I asked for the test - most doctors don't know about it). If you are B12 deficient, then the longer you wait before starting supplements, the more permanent nerve damage you will suffer. If you are not B12 deficient you are extremely unlikely to experience any adverse effects of supplemental B12. As far as I know there are no documented adverse effects.

Martin