Given the amount of scientific literature documenting the strong impact of dietary habits in the outcomes for cancerous diseases, nutritional and dietary guidelines for breast cancer prevention aren’t as solid as they could be. However, this is starting to change. Women can now become aware of another weapon to add in their preventive arsenal. Dutch scientists found strong evidence that the Mediterranean diet—prevalent in Mediterranean countries—reduces the risk of developing hormone-receptor-negative breast cancer in postmenopausal women by 40%. And this is the most lethal breast cancer type.

Large-scale study

More than 60,000 women were followed as part of the Netherlands Cohort Study over a 20-year period. At the beginning of the study, participants were all aged 55 to 69 years old and provided information about their diets and lifestyle. Their medical records from 1986 to 2007 were synchronized with the data in Dutch health institutions that track and collect nationwide cancer statistics.

It was found that the women who followed a Mediterranean diet had a 40% lower incidence of estrogen-receptor negative (or ER-) breast cancer as compared to those who didn’t follow the dietary regimen. Over 3,000 participants in the study developed breast cancer.

According to the researchers, this diet could have prevented one third of ER- breast cancer cases. These findings were cemented after researchers ran a meta-analysis with previous studies.

ER-negative breast cancer is impervious to hormone-based treatments. It is the most difficult to treat and, therefore, the most lethal of all types.

Reportedly, the most beneficial foods were nuts, fruits and fish. These imparted the greatest preventive health benefits against breast cancer. Not surprising given the high availability of omega-3 fatty acids, which are known to offer a powerful protection against breast cancer.

Mediterranean miracle

The Mediterranean diet consists mostly of plant-based foods (legumes, nuts, cereals, fruits and vegetables) with moderate amounts of fish, dairy products and poultry. Red meat is not a significant component of the diet. Olive oil—among the healthiest known to men—is one of the diet’s central pillars. This diet has been shown to promote many health benefits ranging from the promotion of bone and cognitive health to the prevention of cardiovascular and cancerous diseases. It has also been linked with increased life span.

This study reinforces the Mediterranean diet status as one of the healthiest in the world, and could form the basis of awareness campaigns to lower the incidence of this lethal disease.