Is Olive Oil Really So Special?
In the past 25 years, olive oil has taken on the status of a health food. This trend occurred initially among individuals trying to improve their cholesterol levels and protect their heart, but then people who were just generally health-conscious embraced it. Yes, olive oil, like all plant oils, is 100 percent fat—but it's supposedly a "good fat."
A large part of its attraction has come from 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's high in monounsaturated fats, but so are canola oil and "high-oleic" sunflower and safflower oils. Moreover, corn, soybean, and other polyunsaturated oils are actually better than olive oil at lowering LDL cholesterol and, thus, reducing coronary risk. Still, for many health-conscious people, none of these oils compare to olive oil. For them, and for some experts, there are elements besides its effect on blood cholesterol that make it superior—notably the polyphenol compounds it contains.
Why olive oil became hot
In 1958, the famous Seven Countries Study gave olive oil a big boost. Researchers 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.
Which oil is best?
Much research has focused on the relationship between dietary fats and blood cholesterol. It's clear that foods high in polyunsaturated fats lower LDL cholesterol when they replace foods high in saturated fats (such as butter) or refined grain products—monounsaturated fats, less so. That's why the American Heart Association emphasizes polyunsaturated fats in a heart-healthy diet, though it also recommends monounsaturated fats. So if your chief concern is to improve your cholesterol levels, you have nothing to gain by choosing olive oil or another monounsaturated oil over corn, soybean, or other polyunsaturated oils.
What about HDL ("good") cholesterol? It used to be thought that polyunsaturated fats also lowered HDL, while monounsaturated fats did not—or that the latter might even raise HDL. But most research has found that all unsaturated oils, in the amounts commonly consumed, have only a small effect on HDL levels. In any case, some recent studies have led many researchers to de-emphasize the value of raising HDL as a way to reduce heart disease risk.
Other potential benefits
Olives contain polyphenols, a large group of compounds that are found in many plant-derived foods and that have been linked to an array of potential benefits. The less processed olive oil is, the more polyphenols it retains. Extra virgin olive oil is the least processed. Keep in mind that olive oil is hardly unique—polyphenol intake from many foods (notably chocolate, tea, fruits, and vegetables) is associated with a wide range of health benefits.
Aside from its effect on cholesterol levels, olive oil may reduce cardiovascular risk in other ways. For instance, some research suggests that it helps to lower blood pressure (at least a little) and inflammation, as well as to reduce the tendency of blood to clot.
Oils high in monounsaturated fats are less susceptible to oxidation during cooking than polyunsaturated oils. Oxidation promotes the formation of free radicals and other potentially harmful compounds.
Words to the wise
Choose olive oil if you like it, not because you think it's a health food. Canola, avocado, peanut, high-oleic safflower, and high-oleic sunflower oils are also rich in monounsaturated fat. Corn, regular sunflower, peanut, walnut, and other polyunsaturated oils are good choices, too, particularly for their LDL-lowering abilities when they replace foods high in saturated fat, such as butter. Don't forget that all plant oils contain about 120 calories per tablespoon. If you simply add them to your diet, you're likely to gain weight. The trick is to use them to replace other high-calorie foods.