To help my manage my colitis, I am following the "Eat for Your Blood Type" diet. Within the guidelines of the diet, I am allowed to use only green olive oil. What is the difference between green olive oil and extra virgin olive oil?
Green olive oil is not a term used in the industry other than to describe the color. Extra virgin olive oil is usually green to yellow to almost clear. The color does not affect the flavor, nutrient value or acidity. When oil is tasted during competitions or for grading, a special blue tasting glass is used so the color is not visible. Oil from the same variety of olive pressed in the same week can vary in color due to the ripeness of olive, climate, whether leaves got into the press with the olives, etc. To keep well on the shelf, most olive oils are bottled in a dark colored glass or tin which makes buying an oil of a certain color difficult.
It is a mystery where the people who write these diet books get their ideas about olive oil. They are certainly not reading the copious amount of research which has been done over the past 50 years. I have been answering questions on the internet about olive oil for 7 years and every 6 months there is a new book with new claims. "Eat for Your Blood Type" is a fun fad as long as you understand that the vast majority of the doctors, dieticians, chemists and other scientists out there don't see any evidence for the claims. However putting aside the diet, patients with colitis often benefit from reasonable experimentation with diet so I would encourage you to try eliminating or adding different things, including green colored olive oil.
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