Extra Virgin Olive Oil, which is not refined, has been found to contain oleocanthal which is known to interfere with COX-1 and COX-2 enzymes.   Both of these enzymes cause inflammation in the body.  In 2005, a study was conducted on oleocanthal and researchers discovered that it inhibits inflammation in the same way as ibuprofen.  However, it is believed that once Olive oil is exposed to extreme heat many of these benefits are lost.  It would be beneficial to find a way to incorporate the raw oil into your diet, perhaps add it in by mixing your own salad dressings.  Olive oil is a great substitute for vegetable oils and butter.  However, even a healthy oil such as this contains a high amount of calories.  Try to use it moderately especially if you are focusing on reducing your weight to help with arthritis pain.