Mediterranean Diet, Olive Oil Linked to Reduced Risk of Breast Cancer

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Yaneff_150915In a new study published online in JAMA Internal Medicine, researchers have found a link between eating a Mediterranean diet with extra virgin olive oil and a relatively lower breast cancer risk.

Breast cancer is among the leading causes of death in women. Diet has been widely studied as a risk factor associated with breast cancer development. The Mediterranean diet features vegetables, fruit, fiber, olive oil, fish, and other sources of omega-3 fatty acids.

For this study, researchers randomly placed 4,282 women into two dietary intervention groups and one control group. Participants were an average age of 67.7 years and at high risk for cardiovascular disease. From 2003 to 2009, 1,476 women were assigned to a group who were to follow a Mediterranean diet, consuming one liter of extra virgin olive oil weekly; 1,285 women were placed into a Mediterranean diet group consuming 30 grams of mixed nuts (hazelnuts, almonds, and walnuts) daily; and the remaining participants were placed in a control group that received advice to follow a low-fat diet.

During the study, participants had an average body mass index (BMI) of 30.4, the majority began menopause before 55 years of age, and less than three percent used hormone therapy. After a follow-up of about five years, researchers observed 35 new malignant breast cancer cases among participants.

The study authors found that women eating a Mediterranean diet with olive oil reduced their risk of malignant breast cancer by 68% less than the control diet group.

The researchers noted some study limitations. The first was whether the benefits observed were connected to olive oil specifically or the consumption of the Mediterranean diet in general. The authors also lacked information about if and when the women had a mammography. Also, the number of breast cancer cases was low and a diagnosis of breast cancer was not the main reason the women were recruited for the trial.

That being said, the study authors concluded that “the results of the trial suggest a beneficial effect of [the] Mediterranean diet supplemented with extra virgin olive oil in the primary prevention of breast cancer. The intervention paradigm implemented in the 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.”

Sources for Today’s Article:
Toledo, E., et al., “Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial,” JAMA Internal Medicine September 14, 2015, doi: 10.1001/jamainternme.2015.4838.
“Mediterranean Diet Plus Olive Oil Associated with Reduced Breast Cancer Risk,” The JAMA Network web site, September 14, 2015;