The last time I had a checkup the doctor complimented me on my cholesterol levels. She said they were exactly where they should be. I put it down to my fat intake - specifically I go through about 12 ounces of olive oil a month, which is a lot of oil for one person. It is my lipid (fat or oil) of choice and I cook in it, dress salads with it, flavor potatoes with it, dip bread in it, brush grilled sandwiches with it and add it to soups for flavor. At the moment I only have four bottles, but I've had as many as eight.
I know people who are afraid of fat and avoid not only saturated fats like butter and bacon grease, but poly-unsaturated fats like vegetable and corn oil. It's certainly true that if you're watching calories all fats are created equal (120 calories per tablespoon), but while saturated fats contribute to the level of LDL (the Lousy cholesterol) in your blood, monounsaturated fats like olive oil (and omega 3) appear to reduce LDLs and contribute to HDLs (Healthy cholesterol).
But I don't use olive oil for it's health effects, I use for it's flavor.
Olives grow in a Mediterranean climate and and over 90 percent is grown in that area. You probably automatically think Italy, but in fact Spain is the world's largest olive producer and Italy is the world's largest importer. So unless you buying an expensive boutique Italian oil there's a good chance at least part of that Italian oil on your shelf was made from Spanish grapes.
Personally I prefer the oils actually made in Spain and Greece. The ones I like best have a distinct olive flavor, which I prefer to the blander Italian oils. Columela is excellent and, although not cheap, well worth keeping around for it's rich flavor. Goya is also a good Spanish oil (although Cooks Illustrated pans it) and is available in most supermarkets and is cheaper than Columela. I use these two when I want to taste the oil. For most cooking I use Colavita.
These are all labeled "extra virgin," but that doesn't mean a great deal in the U.S. Extra virgin, virgin, pure and so on are European terms and have strict standards applied to oil sold in Europe. But the oil producers can label it super-duper extraordinarily version when the export to the U.S., which uses a different grading system.
You need some fat in your diet to maintain health - although perhaps not as much as many of us eat. However, changing your default from butter or even vegetable oil to olive oil is a flavorful and even healthy way to get that needed fat.