In the beginning cooks used lard, then semisolid shortenings and vegetable oil made their way onto shelves.
Today, the saturated fats from lard (animal fat) and the hydrogenated (trans) fats in shortening have been pushed out of favor and vegetable-based oils have taken over whole aisles at the grocery store. So how to you choose if you want to eat healthy?
According to the science, there is no one "best" oil. All oils have 9 calories per gram (45 calories per teaspoon), and all contain different ratios of monounsaturated, polyunsaturated and saturated fat. Oils consisting primarily of mono and/or poly unsaturated oils still are favored for heart health.
When we investigate the best oils for cooking and baking, however, each has qualities that make them better suited for certain culinary uses. Here's a quick look at the most popular oils on the market.
Canola oil has the best combination of fat sources for both health and cooking purposes. Canola oil is the fifth highest in monounsaturated fat, and it contains more beneficial plant omega-3 fatty acids than any other oil. Canola oil can be used for baking and high temperature frying.
Coconut oil is a saturated fat that does not contain any trans-fat and that makes this oil a better option than shortening. Coconut oil is semisolid at room temperature, but melts at just a few degrees higher so its good for light sauteing and baking. Note there's a taste difference between virgin (unrefined) and refined coconut oil. This oil imparts a sweet nutty flavor and aroma that lends itself to desserts and curries. Scientific evidence remains inconclusive on this oil's health benefits.
Flaxseed oil contains primarily monounsaturated fat and has the added benefit of omega 3 fatty acids. This oil contains high amounts of lignans, chemical compounds found in some plants, which exhibit anti-inflammatory and antioxidant qualities. Flaxseed differs from many of the other oils because it is not heat stable. It's best used for salad dressings, marinades and sauces that do not require cooking.
Olive oil is the highest source of beneficial monounsaturated fat from the list of common oils. It is best used for cooking (especially Italian and Mediterranean cooking), salad dressings and high-temperature frying. It may not be the best choice for baking because it may impart a savory, olive flavor to sweet treats.
Peanut oil is low in saturated fat, free of trans fat and high in monounsaturated fat. Peanut oil can be used for cooking, frying and salad dressings. One unique culinary characteristic of this vegetable oil is that it can be heated to a higher temperature than other oils so the foods in the fryer retain less oil.
Most nut oils are high in monounsaturated fats and walnut, sunflower, safflower and grape seed oils are the highest in polyunsaturated fat.
If you want to substitute oil for butter or shortening in a recipe, use ¾ cup oil for each 1 cup of solid fat. However, baked goods that require whisking sugar with fat (cakes, cookies, frostings) do not work well with oil as the fat source and will result in poorer quality and texture. Heavenly Chocolate Cake is a good place to start experimenting with oils in baking.
• Toby Smithson, a registered dietitian, is the author of "Diabetes Meal Planning and Nutrition for Dummies" and is a national spokeswoman for the Academy of Nutrition and Dietetics.