Dietary vitamin E intake and mammary carcinogenesis in rats

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Abstract
Using the dimethylbenz[a]anthracene-induced mammary tumor model, the present study demonstrated that a low vitamin E intake (7.5 mg/kg of diet) had minimal effect on carcinoma development in rats fed a 5% stripped corn oil diet, but resulted in a marked enhancement in tumor incidence and yield in those rats fed a 25% stripped corn oil ration. Control animals in this experiment received an adequate supply of vitamin E (30 mg/kg as DL-.alpha.-tocopheryl acetate). Thus, the effect of vitamin E deficiency on mammary carcinogenesis was accentuated in rats maintained on a high polyunsaturated fat diet, an observation similar to that of Se deficiency which was reported previously. In view of the biochemical interaction between vitamin E and Se as endogenous antioxidants, another experiment was conducted to determine whether supranutritional supplementation of vitamin E (1000 mg/kg) was able to block the enhancement in mammary tumorigenesis due to Se deprivation. Results of this experiment indicated that vitamin E excess failed to overcome the augmented tumor yield in Se-deficient rats, nor did it provide any protection in rats that received an adequate supply of Se. In summary, vitamin E deficiency may increase the risk of neoplastic development, especially when coupled with a high polyunsaturated fat intake; however, a high vitamin E supplementation does not seem to have any propylactic effect on tumorigenesis by itself.