A new study has reported that a high corn oil diet appeared to increase mammary cancer risk, whereas rats fed a high extra-virgin olive oil diet were more similar to the low-fat diet controls in an animal model of breast cancer. The study authors decided to investigate the effects of high-fat diets on maturation, mammary gland development, and mammary gland carcinogenesis based on previous findings concerning the importance of early-life influences on breast cancer risk. To conduct the study, female Sprague-Dawley rats were given either a low-fat, high corn oil, or high extra-virgin olive oil diet from weaning and administered a carcinogen which normally induces estrogen receptor positive (ER+) mammary tumors in these rats.

Body weight and body mass both were found to increase in the high corn oil group compared to the low-fat group. Puberty occurred earlier in both groups of rats fed high-fat diets, especially the high corn oil group, and the high corn oil group also experienced increased body weight around puberty. Both high-fat diets induced subtle modifications in the form and structure of the mammary gland. The high corn oil diet clearly stimulated cancer development; rats fed this diet developed mammary tumors earliest and had greater numbers and overall mass of tumors than the other groups. The high extra-virgin olive oil diet appeared to have a weak enhancing effect, increasing overall tumor mass. The authors conclude that a high corn oil diet appears to strongly influence sexual maturation and mammary cancer risk, while rats fed a high extra-virgin olive oil diet were more similar to the low-fat diet controls.

Please see our article on how to protect our daughters from breast cancer for more information on how to reduce breast cancer risk early in life.