Olive Oil: It’s Good, but Not Miraculous

In the wonderful world of nutritional hype, olive oil has taken on a special role: It is thought to be the good fat.

During the late 1980s, olive oil was elevated to a position alongside oat bran as a “miracle” food that could actually lower cholesterol. Sales more than doubled between 1985 and 1990, and manufacturers ran high-profile ads stressing the cholesterol-lowering effect of a diet high in olive oil.

But although the research on diets high in olive oil is promising, it’s a long way from conclusive. Even the researchers who conducted the studies have been hesitant to make sweeping generalizations about the results.

It is true, at least, that not all fats are created equal.

Of the several varieties of fat, by far the worst ones, in terms of health, are the ones highest in saturated fat. Solid animal fats such as butter and lard--and vegetable fats such as Crisco--are by far the worst. The less saturated oils (those that do not solidify) are better, but even those vary in the degree of saturation.

Olive oil contains a large quantity of unsaturated fatty acids known as monounsaturated fats, which are even less saturated than polyunsaturated fats. Historically, monounsaturated fats were thought to be neutral in their effect on blood cholesterol, but now they are known to be about as effective as polyunsaturated fat in lowering blood cholesterol when they are used in combination with other dietary modifications, such as lowering the total fat intake, as well as the intake of saturated fat and cholesterol.

The key here is reducing overall fat intake. Adding unsaturated fats to a diet high in saturated fat does nothing but add more fat to the diet. In order to balance your fat intake, no more than one-third should be saturated. The rest should be more or less evenly divided between polyunsaturated and monounsaturated fats.

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Of the common cooking oils, olive oil is among the highest in monounsaturated fat, but it is not the lowest in saturated fat. That honor belongs to canola oil. Using butter as a comparison (66% saturated, 4% polyunsaturated and 30% monounsaturated), you can see where the following oils stand:

* Peanut: 18% saturated, 34% polyunsaturated, 48% monounsaturated;

* Soybean: 15% saturated, 61% polyunsaturated, 24% monounsaturated;

* Olive: 14% saturated, 9% polyunsaturated, 77% monounsaturated;

* Corn: 13% saturated, 62% polyunsaturated, 25% monounsaturated;

* Safflower: 9% saturated, 78% polyunsaturated, 13% monounsaturated;

* Canola: 6% saturated, 36% polyunsaturated, 58% monounsaturated.

So what’s the big deal about olive oil? Well, gourmet cooks have used it for years because of its unique flavor, and certain varieties have taken on a kind of elitist glow that invariably commands a higher price.

The highest grade of olive oil is known as “extra virgin.” In Europe, which is where most of the olive oil originates, this means that the oil must come from the best olives, which are harvested by hand and then squeezed at room temperature. This produces what is known as cold-pressed oil. The oil is then subjected to taste, color and aroma tests that must be met before it can be called extra virgin. If the oil is just a little bit off, it can be called virgin or superfine virgin, but most of this never gets exported.

“Pure olive oil” on the label tells you that the fruit has not been selected as carefully and that a solvent may have been added to take out some of the impurities. The oil is then heated to get rid of the solvent, and the end result is a pale and bland oil. In order to get some of the flavor back, the manufacturers add small quantities of extra virgin oil.

The “light” or “extra-light” oils are not any lower in calories or fat (still 125 calories per tablespoon and 100% fat), but are merely the highly refined oils without any of the flavor added back in. They were developed to cash in on the new market for olive oil among people who believe all the hype but are not fond of the distinctive flavor. The “light” designation is merely about the color.

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The price of olive oils varies enormously, even within categories. However, since almost all olive oils are more expensive than other cooking oils, and since there is probably little if any health difference between them, you may not want to spend the extra money. If you like the taste of olive oil and don’t care about the price, use the extra virgin in cold dishes such as pasta salad or instead of butter on bread.

There are also a number of flavored olive oils on the market that give you a jolt of basil or garlic, for instance. These are particularly good for bread dipping and salads, and their strong flavor means that a little goes a long way.

Most of olive oil’s flavor will disappear if it is heated. If you store olive oil away from the light in a cupboard, it should stay fresh for at least a year. Putting it in the refrigerator does not extend its shelf life and will make it cloudy and thick. If this should happen, let the oil come to room temperature and it will clarify and become pourable.

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Dr. Sheldon Margen is a professor of public health at UC Berkeley; Dale A. Ogar is managing editor of the UC Berkeley Wellness Letter. Send questions to Dale Ogar, School of Public Health, UC Berkeley, Berkeley, CA 94720-7360, or e-mail to daogar@uclink4.berkeley.edu. Eating Smart appears the second and fourth Mondays of the month.