Evaluating the healthfulness of a particular type of fat is a matter of comparison. Though butter is better than margarine and other trans fats, vegetable oils with a blend of polyunsaturated fats or monounsaturated fats, such as olive oil, are even better. These can be used to replace saturated fats in the diet:
Extra-virgin olive oil
A staple of the Mediterranean diet, olive oil has long been associated with a reduction in cardiovascular disease. Extra-virgin refers to oil produced from the first cold pressing of olives — a process that maintains the best flavor and highest levels of nutrients. Olive oil is rich in omega-9 fatty acids, which decrease levels of LDL cholesterol in the blood, as well as phenols, which reduce inflammation and may help metabolic conditions.
A recent trend among California olive growers is the production of artisanal oils from olive varieties that have subtle taste differences. Because olive oil has a low smoke point, the temperature at which heated oil begins to break down and smoke, it's best to use for drizzling over tomatoes or grilled vegetables, making salad dressing or incorporating into pastas and sauces. Olive oil should be stored in a cool, dry place away from direct light.
Fatty, cold-water fish, including wild-caught salmon, herring, mackerel, tuna, lake trout and sardines, are some of the best sources of omega-3 fatty acids as well as excellent sources of protein that is low in saturated fat. Studies have shown that omega-3 fatty acids lower blood pressure, improve cholesterol levels, decrease inflammation and may improve brain function.
The American Heart Assn. recommends eating grilled, baked or broiled fish at least twice a week. Large predatory fish may contain high levels of mercury, so pregnant women and children should avoid eating fish such as king mackerel, sharks and swordfish, and limit low-mercury fish, such as salmon and canned light tuna, to 12 ounces per week. The AHA recommends that people who don't eat fish or those who have cardiovascular disease supplement their diet with capsules containing 1 to 3 grams of fish oil each day.
Canola oil is a multi-purpose oil that has a balanced fatty acid blend. It's derived from crushed rapeseed, a member of the mustard family. Canola oil is high in omega-9 and omega-6 fatty acids and also contains omega-3 fatty acids. Because some varieties of rapeseed have high levels of euric acid, there are misconceptions that canola oil could be toxic. Canola oil is produced from a variety of rapeseed with a very small amount of euric acid, and only trace amounts can be found in the oil.
With a high smoke point and light flavor, canola oil can be used for frying, grilling or searing, in baking or for misting on cookware to create a nonstick surface. Canola oil should be stored in a cool, dry place.
A relative newcomer in culinary fats, avocado oil is a buttery, somewhat fruity oil that is extracted from the flesh of avocados. It has a similar fatty acid profile to olive oil with a high amount of omega-9 fatty acids. Avocado oil is also rich in lutein, which promotes healthy vision. Eating whole avocados provides the same benefits as the oil, along with B vitamins, potassium and additional vitamins and minerals.
Avocado oil can withstand temperatures above 500 degrees, so it's ideal for high-temperature frying or sautéing. It's also delicious for dipping bread, drizzling over vegetables or mixing into a vinaigrette. As a substitute for butter, whole avocados can be mashed on toast with a little salt and pepper.
Walnut oil is a mild, nutty-tasting oil that is extracted from dried or roasted walnuts. Compared with other tree nuts, walnuts are the highest in omega-3 fatty acids and also contain omega-6 and omega-9 fatty acids. Studies show that walnut oil improves cholesterol levels, decreases inflammation and provides a rich source of antioxidants. For maximum health benefits, people can eat whole walnuts; in addition to fatty acids, they provide protein, fiber and vitamin D.
Walnut oil has a medium smoke point, so it can be used for sautéing over medium heat and as a finishing oil over grilled fish or vegetables; it's delicious as a bread dip, tossed in pasta dishes or used in dressing. Its nutty taste lends itself well as a baking fat. Walnut oil has a short shelf life, so it should be refrigerated after opening.
Expressed from the seeds of flax, flaxseed oil contains an abundance of omega-3 fatty acids, though a small percentage can be converted to a useable form in the body. Flaxseeds have a hard shell that is indigestible, so people should either consume flaxseed oil or ground flaxseeds to obtain the benefits.
Because flaxseed oil is unstable, it is best to add to foods after cooking. People can also ingest flaxseed oil in capsules or by the spoonful as a supplement. Ground flaxseed can be added to baked goods or sprinkled over oatmeal, and either the oil or ground seeds can be mixed into smoothies. Flaxseed oil becomes rancid at room temperature, so it should be refrigerated; ground flaxseeds should be stored in the freezer.