Improved delivery of zinc using haptocorrin or intrinsic factor modified to include a zinc binding sequence that can outcompete dietary zinc inhibitors such as phytin. Known zinc binding sequences can be assayed to determine competitiveness with respect to phytin and, if successful, incorporated into the B12 binding site of haptocorrin or intrinsic factor. Thus a method of producing functional human haptocorrin or intrinsic factor which binds to zinc includes the steps of modifying human TCN1 or GIF to comprise one or more zinc-binding site sequences, constructing a vector containing the modified human TCN1 or GIF sequence, and introducing the vector into a host cell for a time and under conditions sufficient for expression of the functional human haptocorrin or intrinsic factor. The resulting zinc binding complex can be orally administered to zinc deficient individuals to improve the amount of dietary zinc available to the individuals.
