Effects of dietary cis- and trans-monoene fats on 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors

The effects of the geometrical difference of dietary fat on mammary tumorigenesis were studied in female rats given purified diets containing either hydrogenated corn oil (trans-monoene fat) or olive oil (cis-monoene fat) at the 10% level and received single oral 7,12-dimethylbenz(a)anthracene (DMBA). The difference in the fatty acid composition of dietary fats was confined essentially to the geometrical isomerism of octadecenoate, and the linoleic acid content was made equivalent (2% of total energy). After about 20 weeks of DMBA treatment, mammary tumor incidence, total numbers of tumors and tumor weight were apparently the same in both fat groups. The results suggest that the trans-monoene fat is equally effective as compared with the cis-counterpart in promoting the development of mammary tumors.