A new study has reported that dietary fish oil prevents DNA damage and reduces proliferation in a rat model of breast cancer. The study was designed to investigate the effect of dietary fish oil on DNA-strand breaks, cell proliferation and anti-cell death protein expression in the development of mammary tumors. The study included 81 female Sprague-Dawley rats, all of whom were administered a carcinogen known to induce mammary tumors. The animals were divided into groups and fed (1) a standard diet plus fish oil; (2) the standard diet plus corn oil; or (3) the standard diet only (control group). Note that the control group was also administered the carcinogen.

The rats given fish oil were found to have 56% fewer single-strand DNA breaks than the control group. On the other hand, the corn oil group had 72% more DNA breaks than the control group. In addition, the fish oil-treated rats were found to have substantially lower Ki-67 (a measure of proliferation), c-Myc (also required for proliferation), and HER2 indices when compared to controls. The corn oil-treated rats had significant increase in these cancer-related parameters. The authors conclude that the results support the hypothesis that omega-3 fatty acids have a role in preventing DNA damage and inhibiting mammary carcinogenesis.