Newswise — Mothers with diets high in omega 6 fats, which are common in the American diet, may be putting their offspring at higher risk for breast cancer at the genetic level, according to a study presented at the American Association for Cancer Research's Seventh Annual International Conference on Frontiers in Cancer Prevention Research.
"We're seeing changes in gene expression up to five months after the animals were exposed to a diet containing omega 6 fatty acids during gestation and lactation," said W. Elaine Hardman, Ph.D., associate professor of biochemistry and microbiology at Marshall University School of Medicine and lead author of the study. "The only explanation is that during gestation and lactation, the mother's diet must be imprinting the genes of the baby."
In this study, researchers fed one group of mice a diet containing corn oil and another group a diet containing canola oil, then recorded the incidence of breast cancer and changes to breast cancer regulating genes in the offspring. All offspring were fed a diet containing corn oil after weaning.
While both groups of offspring were about the same weight, the total tumor weight, number of glands with tumors and fraction of mice with tumors were higher in those whose mothers who were fed corn oil.
The canola oil group also displayed up-regulated genes for CCAAT-enhancer binding protein beta (CEBPÎ²), a transcription factor involved in breast cancer differentiation, and Early growth response 1 (Egr1), a tumor suppressor gene. Down-regulated genes include Bcl2-like 1 (Bcl2l1), an antiapoptotic and Fatty acid synthase (Fas), an enzyme involved in fatty acid synthesis and active in cancer cells. Offspring of the canola oil-fed mothers also showed higher levels of omega 3 fats in the inguinal fat pad, breasts and liver.
Why corn and canola oils? Because 50 percent of corn oil is made up of omega 6 polyunsaturated fats, which have previously been linked to increased rates of breast cancer. In comparison, canola oil has only 20 percent omega 6 fats. Omega 3 fats, which have been linked to lower cancer risk, vary as well. Corn oil has less than .5 percent omega 3 fats while canola oil has 10 percent.
Corn oil's omega 6 percentages also mimic the typical American diet. "Americans now eat a high percentage of omega 6 fats," said Hardman. "In the 1950s and 1960s, doctors began recommending that we switch to polyunsaturated fats to reduce cardiovascular risk, and our diet turned largely to corn and soybean oils as sources of polyunsaturated fats. Soon after those recommendations is when hormonally-influenced cancers " prostate, breast, colon " started going up."
Aside from its omega 6 and omega 3 balance, researchers chose canola oil because of its availability.
"This is a slam-dunk easy change for people to make," said Hardman. "Canola oil is readily available on the grocery shelf, doesn't cost any more than corn oil, and we can use it for all the things we use corn oil. It will help correct some of the omega 3 and omega 6 imbalance. And by changing the mother's diet, we might be able to reduce cancer in the next generation."
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes more than 28,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and 80 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes five major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. The AACR's most recent publication and its sixth major journal, Cancer Prevention Research, is dedicated exclusively to cancer prevention, from preclinical research to clinical trials. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.