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Some olive oils are fake, how to pick the real one

Olive Oild

Believe it or not some olive oil is actually fake. Be careful and watch what oil you are buying from a grocery store.


You are probably already aware of the health benefits of olive oil and maybe have started using it in place of other oils in your meals. But are you buying what you think you are buying? Is your olive oil really an imposter?

Researchers at UC Davis’ Olive Center at the Robert Mondavi Institute tested 52 samples from 14 brands of extra virgin olive oils sold on retail shelves in California. The laboratories evaluated the oils based on standards established by the International Olive Council (IOC).

Extra virgin is the top grade of oil according to the IOC and the USDA. Extra virgin olive oil must have zero defects to be considered top quality. How did the oils fail to meet the standards?

Of the five top-selling imported “extra virgin” olive oil brands in the United States, 73% failed the IOC sensory standards. This means that the oils smelled “musty” or “rancid”. Does this subjective test mean that the oil has gone bad? In most cases, yes.

Oil can become oxidized when it is held at too high of a temperature or is too old. Oil that is oxidized can result in higher cholesterol levels for you, despite its heart-healthy claims.

Most of the top five selling oils – which include Filippo Berio, Bertolli, Colavita, Star and Pompeian – also failed objective measures of quality.

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First, a low level of 1,2-Diacylglycerol Content (DAGs) indicates that a sample is of poor quality or is mixed with cheaper oils (instead of being pure). 70% of the samples tested failed to meet the minimum standard for DAG’s.

Second, oils were evaluated for Pyropheophytins or PPP. An elevated level is another indicator that the oil has been adulterated with refined oils. 50% failed to meet this minimum standard.

Interestingly, two domestic products tested passed at least one of these quality measures without defects noted. These include California Olive Ranch (0% failing DAG) and Cobram Estate (0% failing DAG). Lucini brand failed only 33% of the DAG measure.

Other standards that were tested include Fatty Acid Profile (indicating oil purity) and UV absorption (the more an oil is exposed to light, the more likely it is to become oxidized).

When shopping for olive oil, Dr. Andrew Weil, MD gives the following advice:

  • Buy small bottles of a certified organic oil. Check the label for the ICEA, which means Ethical and Environmental Certification.
  • You can also look for the California Olive Oil Council (COOC) seal which certifies oils as extra virgin. Try to buy the oil from the most recent harvest.
  • Purchase products in dark bottles rather than clear which protects the oil from light.
  • Perform your own sensory test. A top quality oil has a natural peppery finish and a deep “green” aroma similar to grass or artichoke.

Once you find a top-quality oil, be sure to keep it in a dark cool place away from the stove.

Frankel EN, et al. Evaluation of Extra-Virgin Olive Oil Sold in California. April 2011.
Eder K, “The effects of a dietary oxidized oil on lipid metabolism in rats” Lipids 1999 Jul; 34(7):717-25
Dr. Andrew Weil, “How to Choose a Quality Olive Oil”