Nutrition-wise blog

Can the Mediterranean diet prevent breast cancer?

By Katherine Zeratsky, R.D., L.D. September 23, 2015

The Mediterranean diet has long been recognized as an eating pattern that can help ward off heart disease. This Mediterranean diet may also help prevent some types of cancer.

In the Lyon Diet Heart study, participants who followed a Mediterranean diet had a lower risk of all cancers than those who followed another heart-healthy diet. In addition, women in Mediterranean countries have lower rates of breast cancer compared with women in Europe and the U.S.

To investigate the association between the Mediterranean diet and breast cancer risk, researchers in Spain randomly assigned more than 4,200 women 60-80 years of age to a Mediterranean diet supplemented with extra-virgin olive oil (EVOO), a Mediterranean diet with extra nuts or a control diet. The control diet was a low-fat diet. While the women in this group didn't meet the criteria for a low-fat diet, they did decrease all types of fat in their diet.

All of the women in the study ate a consistent amount of carbohydrate and protein. There was a slight increase in the percentage of calories from fat in the diets of women in the EVOO and nut groups. The most significant changes in the diet analysis were:

  • More monounsaturated fats from extra olive oil
  • More polyunsaturated fat from extra nuts
  • Lower mono- and polyunsaturated fats in the control group

The greatest reduction in the risk of malignant breast cancer, a 62-percent reduction, was seen in the women whose diet was supplemented with EVOO. The women whose diet included extra nuts had a small but not significant reduction in risk compared with the control group.

We cannot jump to the conclusion that the monounsaturated fat in olive oil is the reason for the lower risk of breast cancer in this study. It's possible there are other compounds in olive oil that offer preventive benefits. Or perhaps it's a combination of factors. Any way you look at it, though, this looks to be one more win for the Mediterranean diet.

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Sept. 23, 2015