The idea that U.S. supermarkets are rife with adulterated olive oils is an urban legend. You should have every confidence in the authenticity of the olive oil you buy at the store. A study by the U.S. Food and Drug Administration (FDA), whose peer-reviewed research was published in the Journal of American Oil Chemists’ Society, tested 88 extra virgin olive oil samples off the shelves of Washington, D.C.-area retail outlets and found no confirmed adulteration in any of the samples tested. The FDA’s findings mirror the results of the NAOOA's robust monitoring efforts, which sampled an average of close to 200 olive oils annually directly from retail shelves for 20 years.