Eating a Mediterranean diet supplemented with extra virgin olive oil was found to have lowered the risk of breast cancer in a study of women in Spain. The Mediterranean diet is rich in plant foods, fish and especially olive oil.
Miguel A. Martínez-González of the University of Navarra in Pamplona and others analyzed the effects of two interventions with the Mediterranean diet with extra virgin olive oil or nuts compared with advice to women to follow a low-fat diet.
Study participants in the two intervention groups were given EVOO (one liter per week for the participants and their families) or mixed nuts (30 grams per day: 15 grams of walnuts, 7.5 grams of hazelnuts and 7.5 grams of almonds).
From 2003 to 2009, 4,282 women (ages 60 to 80 and at high risk of cardiovascular disease) were recruited. Women were randomly assigned to the Mediterranean diet supplemented with EVOO (n=1,476), the Mediterranean diet supplemented with nuts (n=1,285) or the control diet with advice to reduce their dietary intake of fat (n=1,391).
The women were an average age of 67.7 years old, had an average body mass index of 30.4, most of them had undergone menopause before the age of 55 and less than 3 percent used hormone therapy. During a median follow-up of nearly five years, the authors identified 35 confirmed incident (new) cases of malignant breast cancer.
The authors report that women eating a Mediterranean diet supplemented with EVOO showed a 68 percent relatively lower risk of malignant breast cancer than those allocated to the control diet.
Women eating a Mediterranean diet supplemented with nuts showed a nonsignificant risk reduction compared with women in the control group.
“The results of the PREDIMED trial suggest a beneficial effect of a Mediterranean diet supplemented with EVOO in the primary prevention of breast cancer,” said researchers in their paper.
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, said the authors.
The study has been published in JAMA Internal Medicine.