searching serum zinc cholecalciferol together has not turned up much in the way of useful studies for me, to date. but the other day there was a post made here linking the two - finally!
Vitamin D supplementation modulates blood and tissue zinc, liver glutathione and blood biochemical parameters in diabetic rats on a zinc-deficient diet.http://www.ncbi.nlm.nih.gov/pubmed/22410949
in my case i was looking at things the other way around - my d3 absorption tripled after correcting zinc deficiency. and it does appear that adequate d3 status can be protective against zinc deficiency effects.
zinc's benefits far exceed its interactions with d3... i think we're on the cusp of a huge upswing in mainstream awareness, re zinc's recognized importance in the scientific community. d3 is the perfect gateway, since it's on everyone's radar nowadays.