Olive oil in the diet offers strong protection against breast cancer, judging from a new study that is one of the largest ever to examine the role of diet in breast malignancies.
The research, published this week in the Journal of the National Cancer Institute, found that women who consume olive oil at more than one meal a day have a 25 percent lower risk of breast cancer than those who ingest it once a day or less often.
The research project, a collaboration between scientists at Harvard University and the University of Athens, involved nearly 2,400 Greek women questioned in depth about their dietary habits.
The study also found strong protective effects from high consumption of vegetables and fruits. It reinforces some scientists’ belief that traditional Mediterranean diets are healthier in several important respects than the average American diet.
A similar study from Spain, published last September but little noticed in this country, also found that olive oil consumption was inversely related to breast cancer.
On the other hand, a 1989 dietary study in Italy failed to uncover a protective effect from monounsaturated fat - the type in olive oil.
Dimitrios Trichopoulos of the Harvard School of Public Health, coordinator of the study, stopped short of a blanket recommendation that Americans should sharply increase their use of olive oil.
But he said, “For women we are immediately responsible for - my wife or daughter or sister - I would tell them there may be something there.”
However, he added, “We would never imply that U.S. women should add olive oil to their diet. We suggest substitution of olive oil for other fats.”
The evidence that fruits and vegetables protect against breast cancer was statistically robust, the researchers said.
Specifically, women with the highest fruit intake had 35 percent lower breast cancer risk compared with those with the lowest, while women who consumed the most vegetables had 46 percent less breast cancer compared with the lowest category.