But despite all their advantages and admirers, healthful oils were slow to be integrated into the American diet. Our national cuisine, like our language, derived largely from England, and leaned heavily—you could even say stodgily—toward butter and lard. When we did discover oils, we chose the blandest ones. "Thirty years ago, consumers wanted clear oil with no color, no odor, no flavor—corn oil or safflower," says Matthieu Kohlmeyer, CEO of La Tourangelle, a 150-year-old French manufacturer of nut oils that recently began producing and distributing in the United States. Then, in the 1980s, Americans fell for Mediterranean food and the gorgeous, green-gold oil that pervades it. "Olive oil persuaded Americans that oils could be dark and very flavorful, even cloudy, unfiltered," says Kohlmeyer.
While we now consume twice as much olive oil as we did 10 years ago, we've still barely dipped our toes into the vast world of oils. It doesn't help that the health benefits and risks of the various oils on the market can seem head-spinningly complex—and that many dieters think they should be avoiding fat altogether. The important thing is that our bodies need fat in order to process certain nutrients and build crucial cell membranes, and various oils—especially plant-derived varieties like walnut, avocado, and grapeseed—can impart benefits, such as heightened immunity and lowered levels of bad (LDL) cholesterol.
Keep in mind that different oils have different cooking properties. Most plant oils are volatile, changing quickly from fresh to rancid if not stored in a cool, dark place. Cooking at high temperatures can speed the breakdown of some oils and make them less healthy, or less pleasant-tasting. Oils such as grapeseed and avocado, which have particularly high smoke points—the temperature at which they begin to burn—are the best choices for frying. Most olive oil, meanwhile, is fine for low- and medium-heat techniques like sautéing and baking (olive oil cake is becoming a delicious staple of Italian dessert menus). Damian Sansonetti, the executive chef at Bar Boulud in New York City, poaches certain fish in oils. "Cod, for example, is a relatively lean fish," he says, "and it can be dry if it's pan-roasted. But poached in olive oil, it gets that nice, silky texture." He heats the oil just until "it's warm when you stick your finger in it," then lets the fish cook slowly, until it turns snow-white. Sansonetti also loves to sprinkle pine nut oil on lightly sautéed vegetables and fold hazelnut oil into pureed potatoes, and he adores pastry made with pistachio oil. "Oils add richness and a little flavor to food without altering the texture," he says.
It's not surprising that Sansonetti is such an oil aficionado. When he was growing up in Pittsburgh, his Italian grandmother sought out the finest olive oil available—then rubbed it on her skin. She didn't need a dermatologist, a nutritionist, or a physician to tell her what her ancestors already knew: that the human body is a machine that functions best when well oiled.