Interaction between a semisynthetic diet and indole-3-carbinol on mammary tumor incidence in Balb/cfC3H mice.

This paper extends prior studies on the chemoprotective effect of indole-3-carbinol (I3C) on mammary and endometrial tumors in rodent models and focuses on the interplay between standard laboratory chow (Purina Lab Chow 5001), a high omega 6 fatty acid diet (AIN76A), and I3C on the incidence of mouse mammary tumor virus-induced (MMTV) mammary tumors in mice. While the protective effect of I3C was observed in mice maintained on the AIN76A diet from conception, a marked decrease in tumor incidence was observed, which was found to be directly related to the extent of time the mice were maintained on the Purina 5001 diet prior to the switch to the AIN76A control diet. This protective effect of the chow diet against MMTV-induced tumors has not been previously reported. The effects of the chow diet and I3C do not appear to be additive or synergistic.