New research suggests a Mediterranean diet supplemented with extra virgin olive oil could significantly lower one's risk of developing breast cancer.

The Mediterranean diet is characterized by large quantities of plant-based foods, fish, and olive oil, the JAMA Network Journals reported. It has been linked to a wealth of health benefits in the past, and this new research suggests it could also have a positive impact on cancer risk.

To make their findings, a team of researchers looked at the effects of two interventions with the Mediterranean diet (one supplemented with olive oil and the other with nuts) in a sample of women from Spain; the results were compared with those from another group of women who were advised to follow a low-fat diet. The study used data from the PREDIMED (Prevención con Dieta Mediterránea) trial, which included 4,282 women between the ages of 60 and 80 who were at a high risk of heart disease.

During a median follow-up period of close to five years, the researchers saw 35 cases of newly-diagnosed malignant breast cancer. Women eating a Mediterranean diet supplemented with extra virgin olive oil appeared to have a 68 percent reduced risk of developing breast cancer than women on the control diet. Women who ate a Mediterranean diet supplemented with nuts did not appear to have a significant reduction in breast cancer risk when compared with the control group.

The researchers noted some limitations of their study included: the fact that breast cancer cases were not followed to an end-point; the number of observed breast cancer cases was relatively low; it is not known which trial participants underwent mammography; and the findings do not indicate whether olive oil was the primary driver of reduced breast cancer risk or its consumption as a part of the Mediterranean diet.

"The results of the PREDIMED trial suggest a beneficial effect of a MeDiet [Mediterranean diet] supplemented with EVOO in the primary prevention of breast cancer. Preventive strategies represent the most sensible approach against cancer. 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. Nevertheless, these results need confirmation by long-term studies with a higher number of incident cases," the authors concluded.

The findings were published in a recent edition of the journal JAMA Internal Medicine.