The main type of fat found in all kinds of olive oil is monounsaturated fatty acids (MUFAs). MUFAs are actually considered a healthy dietary fat. If your diet emphasizes unsaturated fats, such as MUFAs and polyunsaturated fats (PUFAs), instead of saturated fats and trans fats, you may gain certain health benefits.
MUFAs and PUFAs may help lower your risk of heart disease by improving related risk factors. For instance, MUFAs may lower your total cholesterol and low-density lipoprotein cholesterol levels. MUFAs may also help normalize blood clotting. And some research shows that MUFAs may also benefit insulin levels and blood sugar control, which can be especially helpful if you have type 2 diabetes.
But even healthier fats like olive oil are high in calories, so use them only in moderation. Choose MUFA-rich foods such as olive oil instead of other fatty foods — particularly butter and stick margarine — not in addition to them. And remember that you can't make unhealthy foods healthier simply by adding olive oil to them.
Also, be aware that heat, light and air can affect the taste of olive oil and possibly its health-promoting nutrients. Store olive oil in a dark, room-temperature cupboard, or even in the refrigerator. The fats and healthy phytonutrients in olive oil — as well as the taste — can slowly degrade over time, so it's probably best to use it within a year or within six months once opened.