Are all olive oils 100% olive oil? An analysis of grades and purity
                                
                                
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                                    6 min read                                
                            
                                According to the North American Olive Oil Association, more than 98% of olive oil on U.S. supermarket shelves is authentic. However, the real question of whether all olive oils are 100% olive oil depends on the grade, as terms like 'pure' or 'light' often indicate a blend of refined olive oils.