Katherine Tallmadge, M.A., R.D., is a registered dietitian; author of "Diet Simple: 195 Mental Tricks, Substitutions, Habits & Inspirations" (LifeLine Press, 2011); and a frequent national commentator on nutrition topics. This article was adapted from one that first appeared in the Washington Post. Tallmadge contributed this article to LiveScience's Expert Voices: Op-Ed & Insights.
The expensive olive oil in your kitchen cabinet is likely not as fresh, nutritious or high in quality as you assume it might be. Does that mean you won't receive the expected health benefits when using olive oil purchased from America's grocery shelves? Possibly.
This issue first came to my attention at a Mediterranean Diet Conference I attended in Florence, Italy, co-sponsored by New York University's Department of Dietetics and the James Beard Foundation.
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"The health benefits of olive oil are 99 percent related to the presence of the phenolic compounds, not the oil itself," said Nasir Malik, research plant physiologist at the U.S. Department of Agriculture (USDA)'s Agricultural Research Service.
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 said.
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 USDA quality standards, according to studies conducted by the University of California at Davis (UC-Davis) Olive Center.