Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Zinc induces metallothionein in the enterocyte, and metallothionein binds copper more tightly than zinc, holding it in the cell until it is shed. This is why formulas that carry meaningful zinc add copper at roughly a 15 to 1 zinc to copper ratio.
Even in chelated form, sustained zinc intake raises intestinal metallothionein and lowers copper uptake. Copper is the standard counterweight in any long-term zinc product.
Ceruloplasmin and its intestinal counterpart hephaestin are copper-dependent ferroxidases that oxidise iron so transferrin can carry it. Without copper, iron cannot leave the enterocyte or the storage cell efficiently.
Absorbed iron still needs copper-dependent ferroxidase activity to load onto transferrin. Copper adequacy is part of what makes an iron dose usable.
High-dose ascorbate reduces copper to its cuprous state and lowers copper absorption and ceruloplasmin activity. Ascorbate with free copper also drives Fenton chemistry, so the two are usually spaced apart.
Molybdenum in the presence of sulfur forms thiomolybdates, which bind copper tightly and remove it from circulation. The antagonism is well described in animal nutrition and carries over to formulation.
Copper and manganese both use divalent metal transporter 1 at the intestinal brush border. Large amounts of one reduce uptake of the other.
Tyrosinase, the enzyme that turns tyrosine into melanin pigment, holds two copper atoms at its active site. Copper is the cofactor and tyrosine the substrate of the same reaction.
Lysyl oxidase, the enzyme that cross-links collagen and elastin fibres, is copper-dependent. Copper supports the maturation step that follows collagen synthesis.
Gluconate is a delivery salt, not a separate nutrient, so elemental copper from both entries adds together. That matters because the tolerable range for copper is narrow.
Dihydrolipoic acid binds transition metals including copper through its two thiol groups. Taken together, some of the copper dose is bound rather than free.