Harvard Health Letters

Q. I've read that olive oil is good for health, but is extra virgin olive oil worth the extra cost, or is it just another trendy gimmick?

A. You probably should be asking a chef, not a doctor. Extra virgin olive oil is trendy -- so popular, in fact, that menus in many high-style restaurants boast of serving "EVOO," the in-crowd's acronym for extra virgin olive oil.

Gentrification notwithstanding, people in the know say that extra virgin olive oil has a characteristic zesty, almost pungent flavor that's missing from ordinary olive oil, which is bland, if less expensive. There is a chemical explanation for the difference between the two types of olive oil, and it may have implications for health as well as flavor.

Like other edible seed oils, olive oil is composed of a mixture of fatty acids. In the case of olive oil, about 75 percent of the fat is oleic acid, a mono-unsaturated fatty acid in the omega-9 group. Oleic acid is also a major constituent of canola oil, and it's equally present in extra virgin and regular olive oil. But there is a difference in the minor components of the olive oils.

Unlike the others, extra virgin olive oil is obtained from the first pressing of olives; the other oils are extracted by solvents, heating, or both. As a result, extra virgin olive oil retains phenols. Various phenols, such as oleuropein, are antioxidants, and they may explain why olive oil helps protect LDL ("bad") cholesterol from the oxidative damage that enables it to trigger inflammatory damage in artery walls. And because of the way it's made, extra virgin olive oil has other vascular, anti-clotting, and anti-inflammatory properties that may be helpful.

A European trial put theory into practice. Two hundred healthy male volunteers were randomly assigned to drink just under an ounce of low-, medium-, or high-phenol olive oil a day. In just three weeks, the high-phenol oil increased levels of HDL ("good") cholesterol and reduced evidence of oxidative stress.

Do these chemical changes translate into clinical benefit and better health? It's too early to say. For that matter, although scientists are confident that olive oil is better for the heart (and prostate) than saturated fat or trans fat, they're not completely sure that olive oil promotes health because of its own properties or just because it displaces harmful fats from the diet.

Until scientists can tell us more, we won't know if the phenols and other minor constituents of extra virgin olive oil actually make a difference for health. But if they make a difference in taste, join the trendy EVOO crowd. The extra cost may even work to your advantage if it helps you resist getting too much of this high-caloric good thing.-- Harvey B. Simon, M.D.

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