Inhibition of tumor growth by dietary zinc deficiency.

Abstract

Summary The effect of different levels of zinc intake on tumor growth was studied by implanting Walker 256 carcinosarcoma into weanling Sprague-Dawley rats maintained on laboratory chow or on a zinc-deficient synthetic diet. Three experimental groups receiving this synthetic diet were given 0, 50, or 500 parts per million, respectively, of zinc ion in the drinking water. The latter 2 groups were pair fed the amount eaten by the unsupplemented group. The survival of rats receiving the zinc-deficient intake was significantly increased compared with the other 2 groups on synthetic diets or the group on laboratory chow. Tumor growth was markedly decreased in the zinc-deficient group and slightly decreased in the zincsupplemented groups compared with control rats on laboratory chow. The reduced tumor growth in the zinc-deficient group was highly significant in a test for specificity of tumor inhibition. Since dietary zinc deficiency inhibited tumor growth, this study demonstrates the importance of zinc for neoplasms. Further investigation is needed on the role of zinc, as well as other essential metals, for malignant proliferation.