In September study results published in JAMA Internal Medicine got a lot of attention: the almost five year study showed women who followed a version of the Mediterranean diet significantly lowered their risk of developing breast cancer.
The clinical trial, known as PREDIMED, randomly assigned about 4,200 women to one of three groups: the Mediterranean diet supplemented with extra-virgin olive oil, the diet supplemented with mixed nuts, or a control group following a regular low-fat diet. Compared to the control group, those on the olive oil diet showed a 68 percent reduction in breast cancer risk, after controlling for variables including age, BMI, smoking, family history of cancer, and physical activity.
But before you grab a bottle of olive oil and a straw, consider the study’s limitations: just 35 women were diagnosed with invasive breast cancer – a small number for analysis – and the women recruited were all postmenopausal and at high risk for heart disease. That’s because PREDIMED’s first purpose was to assess cardiovascular benefits of the Mediterranean diet.
So what could be so special about this diet, and olive oil in particular? Most of us have heard of the Mediterranean diet – full of vegetables, fruits, whole grains and olive oil, and low in dairy products and red meat – known from over a decade of study to improve heart health. PREDIMED and earlier studies show the Mediterranean diet has a favorable effect on blood pressure, lipids, artery plaque, insulin sensitivity and inflammation, lowering the risk of heart attack and stroke.
“What extra-virgin olive oil has are polyphenols, a type of phytonutrient known for strong antioxidant activity,” says Cindy Snyder, MPH, RD, CD. “It also has a unique blend of fatty acids which may reduce the inflammation that leads to atherosclerosis, or hardening of the arteries, and cardiovascular disease.”
Seafood, another staple in the Mediterranean diet, may also contribute to the health benefits of this dietary pattern. Fatty acids known as Omega-3’s – like in salmon, tuna and other fish – are essential for healthy cell function, and the body is inefficient at making them. Phytosterols, a type of natural plant fat that slows the absorption of cholesterol in the body, are found in avocados, nuts, seeds, whole grains and legumes – all of which have a number of other important nutrients.
When considering the known health benefits of the Mediterranean diet alongside very preliminary findings on reducing breast cancer risk, what is the takeaway for women? For starters Cindy advises against focusing on one thing, like olive oil, as a magic bullet.
“For years, researchers have investigated individual food components,” says Cindy. “But, what PREDIMED demonstrates is that a pattern of eating, in which dietary components work together, could improve people’s health.” She points out that the PREDIMED study included specific lifestyle factors associated with the Mediterranean region, requiring participants have at least two meals seated at a table each day, spending a minimum of 20 minutes eating each meal.
In fact, a 2014 multi-study review has linked a “Mediterranean dietary pattern” with a decreased risk of breast cancer. But while the suggestion that a certain diet or oil may help prevent breast cancer is encouraging, more long-term studies specifically targeting breast cancer are needed. Meanwhile, with all the upsides for choosing a Mediterranean diet and virtually no downside, it may just be the diet you’ve been looking for.