High-quality olive oil has trace compounds called phytochemicals that can cause cancer cells to die, according to a report in the journal BMC cancer.

A team of researchers from the Catalan Institute of Oncology and the University of Granada said that phenols found in extra-virgin olive oil stop a gene called HER2 that causes breast cancer.

Other kinds of olive oil lose the beneficial substances when they are treated with heat, according to a news release about the work.

The oils were tested on breast cancer cells in a lab, not in people, and the researchers pointed out that they used concentrations that are much higher than someone could get through food.

But, they said, the results could provide a basis for designing new drugs to fight breast cancer.