Regression of rat primary mammary tumors following dietary d-limonene

The effects of d-limonene on rat mammary tumors were investigated. Following the appearance of mammary tumors induced by 7,12-dimethylbenz[a]anthracene in female (W/Fu X F344)F2 rats, animals were assigned to pairs in which 1 rat was fed a diet containing 10% d-limonene and the other was pair fed an isocaloric diet containing 10% cellulose. There was a highly significant increase in the regression of the first tumors in the rats fed d-limonene. In addition, d-limonene given at this time inhibited the formation of subsequent multiple tumors in these rats.