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Olive Oil, Mediterranean Diet, and Breast Cancer

  More research support for extra virgin olive oil and Mediterranean diet associated with anti-cancer effects - here lower incidence of breast cancer. The Mediterranean diet stresses eating a lot of fruits, vegetables, seeds, nuts, legumes, whole grains, fish, and olive oil. From Science Daily:

Mediterranean diet plus olive oil associated with reduced breast cancer risk

Eating a Mediterranean diet supplemented with extra virgin olive oil was associated with a relatively lower risk of breast cancer in a study of women in Spain, according to an article published online by JAMA Internal Medicine.

The Mediterranean diet is known for its abundance of plant foods, fish and especially olive oil. Miguel A. Martínez-González, M.D., of the University of Navarra in Pamplona and CIBEROBN in Madrid, Spain, and coauthors analyzed the effects of two interventions with the Mediterranean diet (supplemented with extra virgin olive oil [EVOO] 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 (multivariable-adjusted hazard ratio of 0.32) 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 authors note a number of limitations in their study including that breast cancer was not the primary end point of the trial for which the women were recruited; the number of observed breast cancer cases was low; the authors do not have information on an individual basis on whether and when women in the trial underwent mammography; and the study cannot establish whether the observed beneficial effect was attributable mainly to the EVOO or to its consumption within the context of the Mediterranean diet. [The original study.]