Supplementing with zinc over time may cause copper depletion. Real Mushrooms D2Z product only has 30 mg of zinc bisglycinate and advantageously, some mushrooms in culinary or supplement form are a good source of copper. Zinc bisglycinate has been shown to not compete with other minerals for absorption in the gut. A healthy diet or supplementation including copper may be warranted when using zinc long term to ensure proper balance.
Here are some scientific studies for reference:
Yadrick M, Kenney W, Winterfeldt E. Iron, copper, and zinc status: response to supplementation with zinc or zinc and iron in adult females. Am J Clin Nutr 1989;49(1):145-150.
Festa, M. D., Anderson, H. L., Dowdy, R. P., & Ellersieck, M. R. (1985). Effect of zinc intake on copper excretion and retention in men. The American journal of clinical nutrition, 41(2), 285–292.
Fischer, P. W., Giroux, A., & L’Abbé, M. R. (1984). Effect of zinc supplementation on copper status in adult man. The American journal of clinical nutrition, 40(4), 743–746.
Prasad, A. S., Brewer, G. J., Schoomaker, E. B., & Rabbani, P. (1978). Hypocupremia induced by zinc therapy in adults. JAMA, 240(20), 2166–2168.
Samman, S., & Roberts, D. C. (1987). The effect of zinc supplements on plasma zinc and copper levels and the reported symptoms in healthy volunteers. The Medical journal of Australia, 146(5), 246–249.