Scientists say they now know why the Mediterranean diet, rich in olive oil, reduces the risk of breast cancer.
A new study led by Dr. Javier Menendez of the United States says a key ingredient in olive oil, oleic acid, suppresses a gene (HER-2/neu) that is found in many women who develop breast cancer.
Patients with the cancer-causing gene tend to develop the most aggressive form of the disease, and have a poor prognosis for survival.
The researchers say olive oil's oleic acid also improves the effectiveness of a drug (Herceptin) that works against the gene.
Olive oil is a key part of the Mediterranean diet, which also includes a high concentration of fruits, vegetables and bread. Researchers have previously found the diet reduces the risk of heart disease and the effects of aging.