Do Cooking Oil Smoke Points Really Matter? Experts Break It Down

Have you ever accidentally left an oil-greased pan heating on the stove, only to turn around to find billowing smoke filling the air? That means the oil has officially reached its smoke point, or the temperature at which it starts to burn and produce smoke. Aside from the fact that cooking in burnt oil makes for a pretty gnarly-tasting dish, regular exposure to improperly heated oils may have some detrimental effects on your health, too.

We talked to the experts and dug into the science to get the scoop on oil smoke points and how to make sure you're choosing the right oils for your dishes.

Just like there are different types of cooking oils, there are varying smoke points that are dependent on the type of oil.

It's worth noting that while this is a general guideline, the type of processing matters, too. "Clarified and refined oils will have been stripped of most of their fatty acid content and therefore be more resistant to higher temperatures. Oils with high fatty acid content will have smoke points at lower temperatures," says Le. In other words, refined coconut oil has a higher smoke point than raw coconut oil.

As mbg's vice president of scientific affairs, Ashley Jordan Ferira, Ph.D., RDN, shares, "Due to the processing (refining), the refined versions of oils are quite different from the original, native fatty acid profile of the plant oil. That's not a good thing. We want the native plant compounds."

So, why is smoke point important? For starters, low-level exposure to acrolein, the byproduct found in the smoke from burnt oil, can irritate your eyes, nose, and throat1. And while that's acutely unpleasant, the bigger issue is repeated exposure.

"Unfortunately, there is more harm to heating an oil past its smoke point than the irritating smoke it produces," says Lindsay Wengler, M.S., R.D., CDN, CNSC, registered dietitian at Olive Branch Nutrition in NYC. "Not only can an oil heated beyond its smoke point catch fire, but the molecular breakdown of the oil can create pro-inflammatory free radicals and a carcinogenic compound, acrolein, which may be harmful to your health." 

Ferira explains the mechanisms of this problematic aldehyde compound further: "Acrolein is highly reactive and over time can mess with DNA by cross-linking it. It also has the potential to get in the way of essential detoxifying enzyme systems in the liver like cytochrome P450 and throughout the body by inhibiting glutathione pathways."

Regular acrolein exposure has also been associated with heart disease2 and various other diseases3. But the key words here are "regular exposure." The occasional burnt oil isn't a big deal, but you don't want to make a habit of it.

And never reuse heated oil. Reheating oil can create various carcinogenic compounds, including polycyclic aromatic hydrocarbons (PAH), which have been linked to various types of cancer4.

Heating an oil past its smoke point can also negatively affect the flavor of your dishes. "Though we expect a little smoke in the kitchen from time to time, an oil's smoke point is an important thing to consider when cooking as it signals the breakdown and degradation of the oil, including its flavor and nutrient profile," she says, adding that acrolein can add a bitter and/or burnt flavor to your dishes.

Ferira adds, "while some people might enjoy the smoky or burnt smell and flavors (I'm guilty of that sometimes myself), oils smoking and foods charring are actually sensory warnings that we can see, smell, and taste that the oil and foods have been compromised. These things are like acute oxidation and rancidity in real time."

Because smoke points vary so much, you'll want to be discerning about which oils you're using for different types of cooking. Wengler says that since avocado oil has one of the highest smoke points, it's a great option for high-heat cooking. Its neutral flavor also makes it extremely versatile since it won't overpower the taste of whatever you're cooking. It's a healthy oil, too, thanks to its high concentration of antioxidants and oleic acid, a monounsaturated omega-9 fat that is associated with managing weight and preventing heart disease5.

While canola oil, vegetable oil, and soybean oil also have relatively high smoke points, these more unhealthy oils are often highly refined and exposed to potentially harmful chemicals during the refining process, Cate Shanahan, M.D., previously told mbg. When exposed to these chemicals, they lose some of their antioxidants, vitamins, and minerals. They're also chock-full of omega-6 polyunsaturated fats (PUFAs), which can fuel inflammation6 in high amounts over time.

For cool dishes and/or post-cooking drizzling, Wengler recommends extra-virgin olive oil, which has a relatively lower smoke point and is rich in antioxidants and monounsaturated fats. "I enjoy using a high-quality olive oil in cool dishes like salads and yogurt or drizzled over prepared dishes," she says.

Every oil has a smoke point, or the temperature at which the fatty acids start to break down and burn. While repeated exposure to the byproducts from heating an oil past its smoke point can have negative effects on your health (and change the flavor of your food), you don't have to live in fear of occasionally burning your cooking oil. Instead, familiarize yourself with smoke points—and the healthiest oils to use for different types of cooking—and make sure you're always using an oil that's suitable for that purpose.