Olive oil 'fights breast cancer'
11 January 2005

Claims that a Mediterranean diet can ward off breast cancer have been backed by US research, which shows how olive oil can fight the disease.

Scientists from Northwestern University in Chicago, Illinois, have shown that oleic acid, a component of olive oil, can stop a gene linked to cancer from functioning.

The gene, called Her-2/neu, is found at high levels in a fifth of all breast tumours – often signalling that the cancer is aggressive and that the patient's outcome is poor.

"Our findings underpin epidemiological studies that show that the Mediterranean diet has significant protective effects against cancer, heart disease and ageing," said lead researcher Dr Javier Menendez.

The team looked at the effect of oleic acid on breast cancer cells in culture. Laboratory tests showed that the molecule was able to cut expression of Her-2/neu by 46%, they report in the Annals of Oncology.

In addition, oleic acid was found to boost the effects of the monoclonal antibody treatment Herceptin, which targets and destroys Her-2/neu and has been shown to prolong the lives of breast cancer patients.

The researchers suggest that dietary interventions based on olive oil could even help delay or prevent Herceptin resistance developing in breast cancer patients who have elevated the Her-2/neu gene activity.

However, Professor Tim Key, deputy director of the Cancer Research UK epidemiology unit at Oxford University, said that, although previous studies had hinted that Mediterranean-style diets might lower a woman's risk of developing breast cancer, "the data are not consistent and there is currently no strong direct evidence that olive oil can reduce breast cancer risk".

He continued: "This new research shows interesting effects of olive oil on breast cancer cells under laboratory conditions, but much more work will be needed to determine whether this is of any importance for breast cancer in women."