Breast Cancer Protection Starts in the Womb

Hardman studied mice that were genetically predisposed to develop breast cancer.

During pregnancy, the mother mice were randomly assigned to a diet rich in either omega-6 or omega-3 fatty acids. After the baby mice were weaned at 3 months of age, they were again randomly assigned to a diet rich in either omega-6 or omega-3 fatty acids.

All of the baby mice exposed only to omega-6 fatty acids -- in the uterus, while nursing, and after weaning -- developed breast cancer by six months after birth, "which was expected in this mouse model," Hardman says.

"But fewer than 60% of the female offspring with diets rich in omega-3 fatty acids either maternally or after weaning developed tumors by 8 months," she says.

And only 13% of mice who were only given omega-3 fatty acids -- in the womb, during weaning and after birth -- developed breast tumors.

Omega-3s Block Estrogen

Studies have shown that the hormone estrogen fuels the growth of breast tumors. And omega-3 fatty acids block the effects of estrogen, Hardman says. Other protective factors may also be at play.

It's going to take at least two generations to confirm the findings in humans, Hartman says.

In the meantime, Nelson says, there's no harm in talking with your doctor about the benefits of eating more fish, nuts, and other omega-3 fatty acid-rich foods during pregnancy: They're also good for the brain, heart, immune system, and just about all of our body systems, he says.

For pregnant women concerned about ingesting mercurypregnant women concerned about ingesting mercury in tuna and certain other fish, Hardman recommends fish oil supplements.

"But even two servings a week -- the current recommendation for pregnant women -- is still probably three or four times more than the average American gets," she says.

SOURCES: 96th Annual Meeting of the American Association for Cancer Research, Anaheim, Calif., April 16-20, 2005. W. Elaine Hardman, PhD, assistant professor, division of functional foods, Louisiana State University's Pennington Biomedical Research Center, Baton Rogue. William Nelson, MD, PhD, professor of oncology, Johns Hopkins University School of Medicine, Baltimore.