I had mostly been looking at how Vitamin D and A levels were related to increasing zinc, however some research studies showed also that it works both ways as zinc is involved with both Vitamin D and Vitamin A metabolism and function. So that is very important as under inflammation/infection zinc availability and uptake is lowered. A lot makes more sense when you realize the body is switching to an inflammatory state like a see-saw. Here is some more of the Vitamin D relationships.
A sustained raise in plasma zinc concentration (and therefore its potential bioavailability) was obtained only when the zinc was augmented with both vitamins A and D. Seven groups of 10 healthy subjects received various combinations of zinc and the two vitamins A and D, namely: zinc, vitamin A, vitamin D, zinc plus vitamin A, zinc plus vitamin D, vitamins A and D, and zinc plus vitamins A and D. Plasma zinc levels were determined at baseline, 3 weeks and 6 weeks. Plasma zinc levels increased significantly only in the group receiving the combination of zinc and vitamins A and D.
Link The mean Zinc level was significantly lower in the hypovitaminosis D group than in controls. The Pearson's analysis showed a positive and significant correlation between Zinc and 25(OH) D serum levels.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5307609/
Studies have found that reduced blood zinc levels could predict vitamin D deficiency in adolescent girls, while zinc supplementation increased vitamin D levels in postmenopausal women. In vitro studies using human peritoneal macrophages have found that zinc induced the release of calcitriol (1,25-dihydroxycholecalciferol). Zinc also acts as a cofactor for vitamin D functions, as the transcriptional activity of vitamin D-dependent genes relies on zinc to exert pleiotropic functions, including mineral ion regulation. Vitamin D could also induce zinc transporters to regulate
zinc homeostasis.
https://www.sciencedirect.com/science/article/pii/S2665944122000190
The vitamin D receptor (VDR) binds zinc, and the activity of vitamin D dependent genes in cells is influenced by intracellular zinc concentrations. With increasing amounts of Zn(2+), additional Zn(2+) ions were detected bound to VDR and RXR alpha
https://pubmed.ncbi.nlm.nih.gov/11400211/
The glucocorticoid and estrogen receptors are examples of zinc hormonal receptor proteins. They are members of a multigene family that includes receptors for thyroid hormone, retinoic acid, and vitamin D
https://www.science.org/doi/10.1126/science.3283939 The DNA binding domain of these proteins contains zinc. Removal of this element yields hormonal receptors that do not bind DNA when activated by glucocorticoids or estrogens
https://www.mdpi.com/2072-6643/7/12/5542/htm Zinc is required for the DNA binding proteins involved in the regulation of gene expression
https://www.jbc.org/article/S0021-9258(17)43831-2/fulltext https://pubmed.ncbi.nlm.nih.gov/4040853/