There are different types of olive oil in the market like extra virgin, pure, filtered, etc. Each type is derived or made differently so check the label for its origin. Olive oil has a short life so select the one that is fresh and has a recent harvest date. Also make sure that the oil has a seal of approval from the place of its origin to ensure it has passed the quality check. High content of polyphenols (500-800) in an olive oil say that it is healthiest. Filtered olive oil has a longer shelf life as compared to unfiltered so choose according to your needs.