A study of women in Spain suggests that a Mediterranean diet accompanied by supplemental extra virgin olive oil is associated with a lower risk of breast cancer.
A study of women in Spain suggests that a Mediterranean diet accompanied by supplemental extra virgin olive oil is associated with a lower risk of breast cancer. The randomized trial-the first to suggest that a long-term diet can affect breast cancer incidence-is published in JAMA Internal Medicine.
Still, the analysis is from a prior trial with relatively few cases of breast cancer (only 35) and needs to be confirmed with longer and larger follow-up studies, noted the study authors.
The characteristic Mediterranean diet is predominantly plant-based food plus fish and olive oil. Researchers have wanted to address whether this type of diet is linked to a lower incidence of primary breast cancer as observational studies have shown that Mediterranean countries have lower incidence of breast cancer compared to both the United States and Northern and Central Europe.
The study randomized 4,282 women-all between the ages of 60 and 80 and at high risk for cardiovascular disease-to a Mediterranean diet either supplemented with extra-virgin olive oil or 15 grams daily of mixed nuts, or a control diet with advice to reduce fat intake. In the olive oil group, each participant was given 1 liter of olive oil per week for themselves and their family.
After a median follow up of 4.8 years, Miguel A. MartÃnez-GonzÃ¡lez, MD, of the University of Navarra in Pamplona and CIBEROBN in Madrid, Spain, and coauthors found that women who ate a Mediterranean diet with additional olive oil had a 62% lower relative risk of breast cancer compared with those who ate a control diet. The group eating the Mediterranean diet supplemented with nuts had a non-significant reduction in breast cancer risk compared to the control group.
Limitations of the current study were the small number of breast cancer cases among women in the trial, that breast cancer diagnosis was not the primary endpoint of the trial, and the limited information on whether women on study had received a mammogram. Most importantly, the study could not tease out whether it was the Mediterranean diet, the olive oil, or the combination of both that led to the reduced risk.
“The results of the PREDIMED trial suggest a beneficial effect of a [Mediterranean diet] supplemented with extra virgin olive oil in the primary prevention of breast cancer. Preventive strategies represent the most sensible approach against cancer,” stated the authors in their discussion. “The intervention paradigm implemented in the PREDIMED trial provides a useful scenario for breast cancer prevention because it is conducted in primary health care centers and also offers beneficial effects on a wide variety of health outcomes.”