Olive oil’s health benefits? It’s a slippery question

You feel good about using olive oil, right? You know it’s good for you, tasty and easy to use. Still, to get the most benefits — and the best bang for your buck – there’s more you should know.

“The health benefits of olive oil are 99 percent related to the presence of the phenolic compounds, not the oil itself,” says Nasir Malik, research plant physiologist at the U.S. Agriculture Department’s Agricultural Research Service.

(iStock/ISTOCK) - Olive oil.

Gallery

25 recipes under 500 calories: These healthful recipes by Nourish columnist Stephanie Witt Sedgwick are low in calories as well as fat and sodium, based on recommended intake as part of a 2,000 calorie diet.

Malik is referring to the polyphenols in olive oil, nutrients also found in wine, tea, cocoa and many fruits and vegetables that have been discovered over the past decade to be the substances responsible for the bulk of olive oil’s health benefits, without which “you might as well use canola oil,” Malik says.

And when tested, polyphenols were surprisingly low in most commercially available olive oils, according to a recently published study conducted by the Agricultural Research Service, co-authored by Malik.

They also don’t live up to international or U.S. Agriculture Department quality standards, according to studies conducted by the University of California at Davis Olive Center.

The good stuff

Polyphenols decrease heart disease risk factors by lowering blood pressure and cholesterol, reducing blood clotting and improving the health of artery linings.

Researchers have discovered genes that, when activated, either increase or reduce your chances for metabolic syndrome, the name for a group of risk factors that together increase the risk for heart disease, America’s No. 1 killer. Fresh, high-polyphenol olive oil affects these genes in a positive way, reducing your risk for heart disease. But low-polyphenol olive oil does not have the same effects, according to a recent study.

Polyphenols also reduce cancer risk by lowering inflammation and cellular proliferation. They act as antioxidants, reducing oxidation and cell damage, which leads to many degenerative diseases. They even reduce microbial activity and infections.

These benefits explain, in part, why the Mediterranean diet, high in olive oil, has been linked with superior health. But there is an advantage even the poorest of the poor in Mediterranean countries have enjoyed since at least 4,000 B.C.: freshly harvested olive oil. That’s because olives were growing on trees in their own back yards; it was plentiful and cheap. But its freshness had been taken for granted.

Waning quality

Studies show that as days, weeks and months go by after harvest, the polyphenol content and health benefits of the oil diminish.

“Think of olive oil as olive juice with a maximum two-year shelf life,” says Selina Wang, research director at the U.C.-Davis Olive Center.

Several factors are responsible for the polyphenol content of olive oil, according to the experts:

●Harvesting method: Rougher treatment and exposure to the elements reduces phenols.

●The age of the trees: Older trees contain significantly more.

●Olive maturation: Green olives contain more polyphenols than ripe olives, though it’s easier to extract more oil from riper olives.