Mediterranean diet could cut your risk of a hard-to-treat type of breast cancer by 40%

Following the Mediterranean diet could cut your risk of a certain hard-to-treat kind of breast cancer by 40%, says a new study from the Netherlands.

The comprehensive study followed 62,000 women aged 55 to 69 over 20 years. The researchers found a strong link between the Mediterranean diet and reduced oestrogen receptor (ER) negative breast cancer.

ER negative breast cancers aren’t stimulated by the hormone oestrogen, and are often harder to treat, and more likely to spread than ER positive breast cancers.

Around 20 to 25% of all breast cancers diagnosed in New Zealand are ER negative, that’s 1200 – 1500 women diagnosed every year. If we all followed the Mediterranean diet, according to this study, 40% of those cases could be avoided.

The Mediterranean diet is rich in olive oil, fruit, nuts, fish, vegetables and whole grains, and is already known to reduce the risk of heart disease and stroke.

It emphasises limiting red meat, added sugar and refined grains like white rice and white bread.

Usually, the Mediterranean diet involves a moderate amount of alcohol, but because we already know that alcohol increases your breast cancer risk, it wasn’t included in the study. If you’re following the Mediterranean diet to reduce your breast cancer risk, we recommend limiting alcohol as much as possible.

How reliable are these findings?

They look pretty good. The researchers followed a huge group of women – 62,000 – and for a long time. The study relied on women reporting what they ate, which can be inaccurate, but overall, the findings look really promising.

This also study reinforces previous findings. In 2015, a Spanish study instructed a group of women to follow the Mediterranean diet, and gave them 1 litre of olive oil to use every week, and saw a significant reduction in breast cancer cases.

How could following the Mediterranean diet affect my risk?

Around 1200 – 1500 women are diagnosed with ER negative breast cancers in NZ each year, and around 600 of these cases could be prevented if we all stuck to the Mediterranean diet. This study didn’t show any effect of the Mediterranean diet on your ER positive breast cancer risk, which accounts for around 75% of all breast cancers diagnosed in New Zealand.

Aside from breast cancer, the Mediterranean diet is known to reduce your risk of heart disease and stroke, and it’s unlikely to cause you any harm. It’s a great place to start if you want to reduce your breast cancer risk and increase your overall health.

Although we know that a healthy diet and regular exercise can reduce your breast cancer risk, there’s still no way to guarantee prevention. Therefore, it’s important that you know the signs of breast cancer, and show any breast changes to your doctor.