Olive oil is a fat that comes from the fruit of olive trees, and it is constantly cited as a crucial part of a healthy diet.

There are various grades of olive oil, with extra virgin olive oil the highest and most expensive. It also carries more healthful properties than ordinary olive oils; the monounsaturated fat in extra virgin olive oil may lower total cholesterol and low-density lipoprotein, or LDL (the "bad" cholesterol) in blood, according to the Harvard School of Public Health.

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When it comes to cooking, olive oil retains its beneficial attributes, but which types are the best to use when cooking without sacrificing flavor?

Virgin olive oil, which is slightly lower quality then "extra," is ideal for cold dishes or low-temperature cooking, according to Living Green Magazine.

Olive oil with or without the word "pure" in the description is a combination of refined and virgin olive oil. "If the quality of the original oil isn't good enough to be virgin or extra virgin, it is refined to remove the bad odors and flavors and then blended with some virgin to be called 'olive oil' again," North American Olive Oil Association EVP Eryn Balch told Living Green. The heat used in the extraction process leaves this olive oil with fewer antioxidants, while keeping the same amount of monounsaturated fats -- making it a great option for cooking and frying.

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The web site, eatingwell.com echoes the sentiments about using olive oil when making salad dressing or cooking vegetables over a low to medium heat, due to its distinct flavor and higher amounts of monounsaturated fat. But canola oil or something similar is recommended when cooking of over high heat, since olive will lose some of its benefits.

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