(HealthDay News) — A Mediterranean diet supplemented with extra-virgin olive oil may reduce the risk of breast cancer, according to a study published online September 14 in JAMA Internal Medicine.
Estefanía Toledo, MD, MPH, from the University of Navarra School of Medicine in Spain, and colleagues examined the effect of two interventions with Mediterranean diet vs. advice to follow a low-fat diet on breast cancer incidence. A total of 4,282 women aged 60–80 years at high cardiovascular disease risk were recruited to the randomized, single-blind trial.
The researchers identified 35 confirmed incident cases of breast cancer after a median follow-up of 4.8 years. The observed rates were 1.1, 1.8, and 2.9 per 1,000 person-years for the Mediterranean diet supplemented with extra-virgin olive oil, the Mediterranean diet supplemented with nuts, and the control group, respectively. Compared with the control group, the multivariable-adjusted hazard ratios were 0.32 (95% confidence interval, 0.13–0.79) for the Mediterranean diet supplemented with olive oil and 0.59 (95% confidence interval, 0.26–1.35) for the Mediterranean diet supplemented with nuts.
“This is the first randomized trial finding an effect of a long-term dietary intervention on breast cancer incidence,” the authors write. “Our results suggest a beneficial effect of a Mediterranean diet supplemented with extra-virgin olive oil in the primary prevention of breast cancer.”
Several authors disclosed financial ties to the biopharmaceutical industry and to the nut and olive oil industries, which provided the nuts and olive oil used in this study.