NAVARRA, Spain, Sept. 14 (UPI) -- Researchers showed in a new study that a Mediterranean diet that includes extra virgin olive oil can help prevent breast cancer.
The Mediterranean diet -- known for containing more fish or white meats, and leaning heavily on fruits, vegetables and whole grains -- has been shown by previous studies to lower the risk of heart and stroke and to generally be a healthier option.
The study was conducted as part of larger researcher into the diet at the Prevention with Mediterranean Diet program at the University of Navarra in Spain.
"All this despite the fact that the control group, or comparison group, followed an already health diet," said Dr. Miguel Angel Martinez-Gonzalez, a researcher at the University of Navarra, in a press release. "Which suggests that the results could have been even more significant had it been compared to a dietary pattern as the followed in non-Mediterranean Western countries."
Researchers recruited 4,282 women between the ages of 60 and 80 who are at high risk for cardiovascular disease, prescribing them a diet and following them for 5 years. The women were randomly split into three groups: One ate a Mediterranean diet supplemented with extra virgin olive oil; one group's diet was supplemented with nuts; and the third group ate the diet but were advised to cut back on dietary fat.
They found that the group of participants that ate the diet supplemented with extra virgin olive oil had a 68 percent lower risk of malignant cancer than the group eating a standard Mediterranean diet. The difference between the group that had extra nuts and those advised to cut back on fat were statistically insignificant, the researchers reported.
During the five-year follow-up period, researchers identified 35 women who'd developed breast cancer.
The researchers noted the study had weaknesses -- the women were not all screened for breast cancer with mammograms, they were not blinded to the type of diet they received, and were all white, postmenopausal, and at high risk for cardiovascular disease -- but that the Mediterranean diet showed clear benefits against breast cancer regardless.
"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," the researchers wrote in the study. "Nevertheless, these results need confirmation by long-term studies with a higher number of incident cases."
The study is published in JAMA Internal Medicine.