The secret ingredient to the Mediterranean diet

An old adage states that, of all the cultures in the world, Italians are the healthiest and live the longest. Despite being an anecdotal claim, there may be some truth to it after all. Italy ranks among the top five countries on earth in terms of life expectancy. It’s also known as one of the five Blue Zones, which are geographically defined areas with the highest percentage of people who live to be over age 100. What’s the secret?

One dietary consistency that is common in Italy and in other Blue Zones is the consumption of olive oil. 

A liquid fat obtained from olives, olive oil is widely recognized as a healthier alternative to butter and margarine. But what makes this fruit oil the superior dietary fat?

Modern olive oil is made by pressing olives and then extracting the oil from the pulp using a centrifuge. Understanding the quality of the oil you purchase is important because not all oils are made equally. In general, extra virgin olive oil (EVOO) is considered to be the highest grade because it has been processed the least, has fewer chemicals and free radicals, and has a higher concentration of antioxidants. 

The beneficial properties of olive oil have been most directly attributed to its high monounsaturated fatty acid content. However, recent evidence suggests that other characteristics of EVOO, such as its phenolic compounds, may also provide significant health benefits. 

Benefits of olive oil

Consumption of olive oil, specifically virgin and EVOO, has been associated with a lowered risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes, and hypertension. Researchers also showed it has positive effects on health factors that predispose people to cardiovascular diseases, including blood pressure, lipid profile, and endothelial function.

To test the cardioprotective effects of olive oil, one recent study published in Circulation measured the cumulative olive oil intake of more than 60,000 women from the Nurses’ Health Study and 35,000 men from the Health Professionals Follow-up Study who were free of cancer, heart disease, and stroke at baseline. After 24 years of follow-up, the researchers concluded that compared with non-consumers, those with higher olive oil intake had a 15% lower risk of cardiovascular disease. Interestingly, substituting butter, margarine, and mayonnaise with olive oil also produced a lowered risk of cardiovascular disease overall.

Delving deeper into the biochemistry of olive oil, findings in the Oxidative Medicine and Cellular Longevity journal conclude that polyphenols—plant metabolites—found in olive oil possess protective benefits against atherosclerosis, brain dysfunction, stroke, and cancer. Due to their anti-inflammatory properties, the dietary consumption of polyphenols was shown to be inversely associated with cardio- and cerebrovascular diseases, such as hypertension and stroke. Besides olive oil, other food sources of polyphenols include vegetables, coffee, red wine, and black and green teas.

While olive oil alone has undeniable benefits, it’s important to highlight one particular diet that features olive oil as its key component. The Mediterranean diet—with its emphasis on plant foods, healthy fats, and whole grains—is consistently lauded as the gold standard diet in terms of health. The purported benefits of the Mediterranean diet are many, from higher life expectancy to decreased incidence of depression. Unsurprisingly, the Mediterranean Diet is also consistently linked with a reduced risk of chronic disease.

One study testing the efficacy of the Mediterranean diet followed 3,500 patients with high cardiovascular risk. The patients were put on one of three diets: a Mediterranean diet supplemented with EVOO, a Mediterranean diet supplemented with nuts, or a control diet. Results confirmed that a Mediterranean diet enriched with EVOO was the most effective in terms of reducing diabetes risk.

In another study of this diet pattern, an inverse association between adherence to the Mediterranean diet and cardiovascular risk was found. This randomized trial in the New England Journal of Medicine involved more than 7,000 people in Spain and found that those given either a liter of EVOO or 200 g of walnuts, hazelnuts, and almonds every week for 5 years had a significantly reduced risk of stroke and heart disease, compared with a third control group who were simply advised to have a low-fat diet.

Why olive oil alternatives don’t match up

The idea that some fats are “good” and others are “bad” is not so straightforward, but the prevailing understanding is that foods rich in mono- and polyunsaturated fats (like olive oil) will lower your heart disease risk and foods high in saturated fat (like butter and mayonnaise) will not lower heart disease risk. In choosing to consume butter, mayonnaise, or margarine, the saturated fat content raises LDL cholesterol. In comparison, olive oil consumption actually lowers LDL cholesterol due to its high concentration of monounsaturated fat.

Frank Hu, MD, professor of nutrition and epidemiology at Harvard School of Public Health (HSPH), published a landmark epidemiological study in the New England Journal of Medicine when he was a postdoctoral fellow at HSPH. His data, collected from 80,000 women enrolled in the Nurses’ Health Study, suggested that replacing a mere 5% of saturated fat calories with unsaturated fat would reduce one’s risk of heart disease by 42%.

“There was really a paradigm shift in terms of the fat message,” Dr. Hu told Harvard Public Health Magazine. That message: “Not all fats are created equal.”

Similarly, a clinical trial published in BMJ Open had participants consume 50 g daily of either butter, olive oil, or coconut oil, over 4 weeks. The outcomes showed that LDL cholesterol concentrations were significantly increased in those who consumed butter compared with those who consumed olive oil and coconut oil. The differences between olive oil and coconut oil were not significant.

While olive oil may be more nutritious than competing dairy fats, it is still a fat that should be consumed in moderation. When it comes to determining what kind of quality olive oil you are purchasing, be sure to inspect labels carefully and to purchase from a reputable seller.