Is olive oil good for my health?

Olive oil consists of monounsaturated fatty acid oleic acid and several antioxidant agents that may account for some of its health benefits. Olive oil is particularly valued for its protection against heart disease because it lowers the harmful low density lipoprotein (LDL) cholesterol and increases the level of protective high density lipoprotein (HDL) cholesterol. It also helps in circulating LDL cholesterol from being damaged by free radicals and contributes to better control of the elevated blood triglycerides that are common in diabetes.

In ancient Greece, the physician Hippocrates prescribed it for an array of ailments, and many people today regard it as the most healthful type of vegetable oil. While olive oil does appear to have health benefits, the claim that it's superior to all other oils is a bit slippery.

A key part of the so-called Mediterranean diet, olive oil is often singled out because it's high in monounsaturated fat. But it's also lower in polyunsaturated fat than other common cooking oils like canola, safflower and corn. Both monounsaturated and polyunsaturated fats are considered "good" fats that may reduce the risk of heart disease.

Which of these fats is better for us is unclear. Some research suggests that polyunsaturated fats may have an edge when it comes to lowering LDL (bad) cholesterol, while monounsaturated fats may result in higher HDL (good) cholesterol. A meta-analysis of 14 studies called it a draw, concluding that replacing saturated fat with either monounsaturated or polyunsaturated fat has an equally beneficial effect on cholesterol levels.

Another meta-analysis, this one of 11 cohort studies, went a step further, looking at heart attacks. And here the news wasn't good for monounsaturated fat: Substituting it for saturated fat was associated with an increased risk of heart attacks, while polyunsaturated fat was linked to lower odds. While these results aren't necessarily an indictment of olive oil -- the research lumped it in with other sources of monounsaturated fat like animal fat, which could have different effects -- they poke holes in the notion that its high levels of monounsaturated fat make olive oil more healthful.

Some people point to olive oil's lower levels of polyunsaturated fats as an advantage when it comes to cancer. In fact there's some research linking certain kinds of polyunsaturated fats (specifically so-called omega-6 fatty acid, as opposed to omega-3 fatty acid found in fi sh) to breast, prostate, and other cancers. But overall, the findings are conflicting and far from conclusive.

Another theory is that antioxidants in olive oil known as polyphenols make it more healthful than its rivals. Research suggests that virgin and extra-virgin oils, which are high in polyphenols, may be more heart healthy than refined olive oil. But the evidence is preliminary and doesn't shed much light on how virgin oils stack up against non-olive oils.