Is olive oil really that special?
In the past 25 years, olive oil has taken on the status of a health food, initially among those trying to improve their cholesterol levels and protect their heart, but then also among people who were just generally health-conscious. Yes, olive oil, like all plant oils, is 100 percent fat—but supposedly a “good fat.” A large part of its attraction has been due to accumulating research about the health benefits of the Mediterranean diet, of which olive oil is a key element. Smart marketing has played a big role, too. The olive oil industry has sponsored lots of research and deftly promoted its product to consumers as well as nutritional experts.
Olive oil is sometimes promoted because it is high in monounsaturated fats, but so are canola and “high-oleic” sunflower and safflower oils. And the fact is that corn, soybean, and other polyunsaturated oils are better than olive oil at lowering LDL (“bad”) cholesterol and thus reducing coronary risk. Still, for many health-conscious people, none of these oils compare to olive. For them, and for some experts, there are other things about olive oil besides its effect on blood cholesterol that make it superior—notably the polyphenol compounds it contains. Let’s take a closer look at the olive oil story.
Why olive oil became hot: observational studies
Olive oil has been the basic edible oil in regions around the Mediterranean since the Bronze Age. Three thousand years or so later, in 1958, the famous Seven Countries Study gave olive oil a big boost. It observed that men who had low intakes of saturated fats had the lowest blood cholesterol and the lowest rates of heart disease (heart studies didn’t include women back then). Strikingly, the very lowest rates were found in Greece, on the isle of Crete, where the diet was relatively high in unsaturated fat, which came primarily from olive oil.
Keep in mind, however, that these Greeks did lots of heart-healthy things— consuming mostly plant-based foods, moderate amounts of wine and fish, and very little meat, as well as doing hard physical work—so it’s difficult to know how important olive oil was. Note, too, that the Japanese, who consumed no olive oil, were also found to have a very low rate of heart disease.
Many subsequent observational studies also linked the traditional diets of various Mediterranean countries, all of which use olive oil as the primary fat, to cardiovascular and other benefits, including reduced mortality rates.
An important Spanish dietary trial called PREDIMED (Prevención con Dieta Mediterránea) was designed to determine the long-term effects of versions of the Mediterranean diet in people at high cardiovascular risk. Participants were divided into three groups: Mediterranean diet plus additional olive oil; Mediterranean diet plus nuts (30 grams a day); or a lower-fat diet (the control group, still basically Mediterranean).
The first study to come out of the PREDIMED trial was published in 2013 and showed that after five years both the olive oil and nut groups had fewer cardiovascular events than the control group, especially fewer strokes in the nut group. More recently, follow-up PREDIMED studies have linked the Mediterranean diet enriched with olive oil to a variety of benefits, including a reduced risk of cognitive decline, breast cancer, and osteoporotic fractures.
It’s uncertain, however, how big a role olive oil played in PREDIMED, since the control group consumed nearly as much (averaging three tablespoons a day) as the olive oil group (four tablespoons). It’s also not known how other oils might have compared.