It’s dinnertime. You’ve chopped the onions, turned on the stove, and you need to add some oil to the pan.

But which one to use?

The average American consumes more than 53 pounds of cooking oil a year, which means your choice of oils has a big impact on your health.

Most nights you probably reach for a vegetable oil (like canola or olive), but not all oils are created equal, and different oils are better suited to different types of cooking.

Learn the Oil Lingo

Refined. Cold-pressed. Extra-Virgin. What do these words mean?

Most vegetable oils are squeezed out of seeds, nuts, or fruits, which sounds healthy, but some methods can create a product that is unhealthy. Just like other foods, look for oils that are fresh and have the least amount of processing.

Refined oils go through a process that often involves heat or chemicals (or both), which can remove nutrients and leave a final product that oxidizes (goes rancid) quickly. Deodorizers are often used in the refining process, so it can be difficult to know when an oil goes rancid. Oxidized oils can cause a number of health problems. Some refining processes use lower temperatures and less chemicals, but it is nearly impossible to discover this information as there isn't consistent labeling in the industry.

Expeller-pressed oils are extracted through a mechanical process. Cold-pressed oils are expeller-pressed at a low temperature to keep more nutrients intact. 

Unrefined oils are simply pressed and bottled. You may see sediment in these oils; it's harmless. These oils have stronger flavors and degrade quickly in heat.

Virgin or extra-virgin are labels traditionally reserved for olive oil, but they're showing up on other oils, too. These labels mean something slightly different depending on which country you're in, but generally, virgin and extra-virgin olive oils come from the first pressing of the fruit and contain less than 2% and .8% fatty acids, respectively.  

Turning Up the Heat

Now that you know how to better understand the label, it's time to match your oil with your cooking method. Some oils withstand high heat while others are better suited for low-temperature cooking or fresh use.

Delicate oils, including many expeller-pressed and cold-pressed oils, oxidize quickly when heated, making them unhealthy. You may not notice the bad taste of an oxidized oil because it gets overpowered by other foods.

Even olive oil can lose valuable nutrients when heated. If you love olive oil, sauté your vegetables in water first and add the oil after you've turned off the heat. You'll be able enjoy more of its flavor this way, too.

Alternatively, cook with coconut oil (or butter), which is naturally full of medium-chain fatty acids that stay more stable when heated. Research shows coconut oil also helps with weight control.

This list from Rodale News suggests which oils work at various temperatures.  

 High Heat 
 (445° to 520° F)

  Refined versions of almond, avocado, and sesame oils

 Medium-High Heat 
 (360° to 425° F)

  Refined coconut, and walnut oils and unrefined safflower oil

 Low to Medium Heat 
 (280° to 350° F)

  Unrefined versions of coconut and sesame oils and all olive oils

Assess Your Oils

Here is a list of popular oils and some important things to know about each one. All oils should be stored in a dark container in a cool, dark, dry location. Oils can be stored in the refrigerator (some, like flax seed oil should be stored there), but seal them tightly so they don't absorb unwanted smells.

Avocado Oil
Made by pressing the fruit of avocados, this oil is high in both monounsaturated fat and Vitamin E and can help aid in the absorption of nutrients. While this oil is typically more expensive than others on the market, a little goes a long way.

Canola Oil
Canola oil is made from a variety of rapeseed (a plant in the mustard family), and is typically produced using high levels of heat and chemical deodorization. It is low in saturated fats and offers a neutral flavor in cooking. About 90% of the canola grown in the United States is from genetically modified seeds, according to the Non GMO Project. Use this oil sparingly and buy organic or look for a Non-GMO Project verified oil if you are concerned about consuming GMOs.

Coconut Oil
Despite being a saturated fat, coconut oil has antifungal and antibacterial properties and is high in lauric acid, which can help boost your immune system. Look for extra-virgin coconut oil for baking purposes and expeller-pressed coconut oil for sautéing.

Flax Oil
Flax oil comes from the tiny seeds of the flax plant and is known for its high alpha-linolenic acid content. This oil oxidizes easily so is often packaged in dark bottles and refrigerated. A recent favorite in health circles for its potential anticancer affects, flax has become controversial due to its phytoestrogenic lignan content, which in high doses has been shown to stimulate cancer cells in women with a history of estrogen-sensitive cancer.

Hemp Oil
Hempseed oil comes from the seed of the cannabis hemp plant, but does not contain the psychoactive compounds of its cousin. This oil is high in omega-6 and omega-3 polyunsaturated fatty acids. It should be kept away from heat—store it in the refrigerator or even the freezer, and use it fresh rather than in cooking. Unrefined varieties have a rich, nutty flavor and are well-suited for salad dressings.

Olive Oil
Extra-virgin olive oil is made from applying pressure to olives to squeeze out the delicious oils. The more flavor your olive oil has, the less processing it has undergone. Extra-virgin and virgin olive oils are better for salad dressings and low heat, while a more refined olive oil can withstand more heat but will have less flavor.

Peanut Oil
Since peanut oil has such a high smoke point, according to the Culinary Institute of America's The Professional Chef, it is traditionally used in Asian-style cooking, where high heat is necessary (think hibachi and stir-fry) as well as for frying foods. Peanut oil has a mild flavor that is almost neutral, but be mindful of those allergic to peanuts when using it.

Sesame Oil
This toasty-tasting oil comes from sesame seeds and works great in stir-fries and other Asian-style dishes. It has natural antioxidants that help keep it from going rancid.

Soybean Oil
A component of margarine and shortening, this highly processed oil makes its way into most commercial recipes. The most ubiquitous oil of the food industry, soybean oil makes up about 90 percent of oilseed production in the United States, according to the USDA. Most soybeans grown today are bioengineered, a fact that has created a lot of controversy around individual and environmental health. As it is high in polyunsaturated fatty acids, keep this oil away from heat.

Sunflower Oil
Made from pressed sunflower seeds, this oil is high in monounsaturated fat and tends to be less processed than canola oil. It offers a more neutral taste than olive or canola. Look for organic and unrefined versions if you want your oil pesticide-free. 

Walnut Oil
This delicate, nutty oil is very perishable, but it is high in omega-3 fatty acids. It’s better for low-temperature cooking or in salad dressings, because when it's heated it can have a bitter flavor.