Rancid Olive Oil May Be Hazardous to Your Health, Experts Suggest

We’ve trumpeted why fresh extra virgin olive oil is important. It smells and tastes great! But the importance of fresh oil has taken on additional meaning: Rancid oil may be bad for your health, experts quoted in a recent newspaper article suggest.

What’s wrong with eating rancid oils? Chicago Tribune reporter Monica Eng asks in her story. (Click here to see the article.)

“There are at least two (problems),” lipid specialist and University of Massachusetts professor Eric Decker told Eng. “One is that they lose their vitamins, but they also can develop potentially toxic compounds” that have been linked to advanced aging, neurological disorders, heart disease and cancer.

Integrative medicine specialist Andrew Weil also told Eng: “They’re carcinogenic, pro-inflammatory and very toxic. … They are also widespread in the food chain.”

It’s sobering food for thought. And it comes as Americans, who’ve long bought olive oil from large European producers, apparently have become accustomed to rancid oils.

In a study published last year, 74% of northern California consumers surveyed said they disliked bitter and pungent olive oils – qualities favored by expert olive oil tasters. By contrast, 44% liked the olive oils that had rancid flavors. The survey was conducted by the Olive Center at the University of California’s Davis campus. (Click here to see the study.)

“We suspect that the consumers who liked the defective oils’ qualities were accustomed to those flavors because many of the imported oils they consume are rancid to begin with,” UC Davis professor Jean-Xavier Guinard said. Guinard, a professor in the Department of Food Science and Technology, was one of the study’s co-authors.

A U.S.-Australian study last year suggested that “most” top-selling European “extra virgin” oils sold in California supermarkets “regularly” fail to meet international standards for extra virgin. Extra virgin olive oil is the top grade, delivering the best taste and the full health benefits of olive oil. It also commands the highest price. (Click here to read the study.)

The researchers found that nearly three-quarters of the top five imported brands failed to pass “blind” taste tests conducted by two panels of professional tasters.

To keep our olive oil fresh, we harvest the olives and rush them to our mill in a matter of hours so they can be crushed into oil as soon as possible. We store the oil in tanks engineered to keep out heat, light and oxygen. We also bottle the oil in dark green bottles to protect them from light.

“Light, together with heat and oxygen, is one of the enemies of olive oil,” author and olive oil export Tom Mueller told us recently. “Light causes olive oil to degrade. So dark glass that filters out light is very important.” (Click here to see a Q&A with Tom Mueller.)

At home, store your oil in a cool place that’s away from heat and light. Remember, the top of the stove is a lousy place to keep your oil: It gives off heat!

One other point worth noting: On the back of our bottles, we print the date the olives were harvested as well as the “best by” date for using the oil. It’s information you can use to ensure the oil you get is fresh – versus rancid.

Your friends at California Olive Ranch