Q. What is the healthiest oil to cook with?

A. Relative to other oils, canola (made from the seeds of a yellow-flowered plant) and olive oils are rich in monounsaturated fats—the kind that help reduce “unhealthy” LDL cholesterol and boost “healthy” HDL cholesterol. But new research suggests that virgin (and extra-virgin) olive oils—those produced purely by mechanically pressing the oil from olives, with no chemical processing—have an edge: antioxidants called polyphenols. Naturally found in olives (in red wine and green tea too), polyphenols mop up free radicals before they can oxidize LDL (oxidation makes LDL even more damaging to arteries).

In a three-week study of 200 men published recently in Annals of Internal Medicine, those who consumed just under two tablespoons a day of high-polyphenol virgin olive oil in place of other dietary fats registered larger increases in “good” HDL cholesterol and fewer markers of oxidative stress than men who consumed the same amount of “ordinary” olive oil, which had a very low polyphenol content. Chemical refining processes remove some polyphenols from “ordinary” olive oils (often labeled as “pure” in the U.S.) and other cooking oils, says Maria-Isabel Covas, Ph.D., lead author of the study and a researcher at the Municipal Institute for Medical Research in Barcelona, Spain.

Bottom line: Virgin olive oil doesn’t just taste better than plain old “olive oil,” it’s better for you too. (Great justification for splurging on a pricier product, no?) That said, any olive or canola oil is a heart-healthy choice—assuming you use it as a substitute for (not a complement to) saturated fats in your diet. If cost is a concern, go ahead and use refined olive oil or canola in cooking and save the virgin oil for cases that call for a high-impact fruity flavor (dipping bread, dressing salads, accenting soups).
—D. Milton Stokes, M.P.H., R.D.