yep, if you've been taking zinc, your b12 absorption from food and supps should be better. your vit b12 does not look excessive - just higher than the norm seen in tests done at that lab.
i saw one study where 615 pmol/L was the mean value in subjects tested.
(Reference values for serum folate, erythrocyte folate and serum cobalamin in Nigerian adolescents.)
not sure what units your vit b12 results are in. so if your result was 765 pg/mL that would be 564 pmol/L.
some researchers have suggested that 500-550 pg/mL (~360-400 pmol/L) should be a minimum
(Are U.S. Lower Normal B12 Limits Too Low?)
you wouldn't believe the hoops i had to jump through back in the day to get the long form of this snail mailed to me :S even while i still enjoyed full text access.
lucky us, these days someone has copied it to a different host:http://alzheimers2ndopinion.net/b12limits.htm
"These reported [neurocognitive assessment] NCA deficits have proved to be a consistent pattern in identifying four previous, similar cases of reversible (350-400 pg/mL) vitamin B12 dementias in our clinic.... As with other reports, this case supports the notion that mental manifestation of B12 deficiency can precede hematologic abnormalities. A IV-stage model of the development of B12 deficiency has suggested that myelin or other neurological damage can occur in the first two stages when B12 levels can still be within the "normal" range." [ie, before hematologic abnormalities such as increased mean corpuscular volume are observed]