Skip the soybean oil: Which cooking oils are actually good for you?

No Chuseok celebration is complete without jeon — savory pancakes sizzling in a pan of hot oil. But the type of oil used to fry them matters more than most people realize, because heat changes the chemical properties of cooking oils.

Recent research on cooking oils has confirmed that heating triggers oxidation, polymerization and hydrolysis, and that the higher the temperature, the greater the degradation.

Soybean oil, one of the most commonly used options, is hard to recommend for high-heat cooking. It is rich in linoleic acid, a polyunsaturated fatty acid that oxidizes readily under prolonged heat, producing aldehydes and other oxidation byproducts. The process accelerates when oil is heated at high temperatures for extended periods — as in deep frying — or when the same oil is reused multiple times. Telltale signs of degradation include changes in color and smell, as well as a thicker consistency.

So which oils hold up better when the heat is on?

For years, conventional wisdom held that olive oil should never be heated — and that extra-virgin olive oil belonged exclusively in salad dressings. That view, however, does not hold up to scrutiny.

Olive oil is rich in oleic acid, a monounsaturated fatty acid. The Harvard T.H. Chan School of Public Health lists olive oil and canola oil among plant-based cooking oils high in unsaturated fats.

Studies comparing heat stability have also found olive oil performs relatively well. One study found that various types of olive oil resisted oxidation during frying better than common vegetable oils. Another found that refined olive oil showed greater resistance to oxidative degradation than several refined seed oils.

The right choice, however, depends on the dish. Extra-virgin olive oil has a strong, distinctive flavor that can alter the taste of food. For mild-flavored jeon, refined olive oil — which has a more neutral aroma — is the more practical option.

Avocado oil is another solid choice for high-heat cooking. Like olive oil, it is rich in oleic acid. Refined avocado oil in particular has a relatively high smoke point, making it suitable for stir-frying and grilling, where temperatures run higher.

Its mild flavor is an added advantage — it does not overpower the natural taste of ingredients, making it a good fit for jeon and stir-fried dishes alike. That said, avocado oil is not immune to oxidation; prolonged heating at high temperatures or repeated reuse will still cause it to degrade.

This is not to say avocado oil is unconditionally healthier than other cooking oils. Its appeal lies in its high monounsaturated fat content and its suitability for high-heat cooking, making it a worthwhile option to consider — particularly for frying and pan-cooking where oil temperatures climb.

Rice bran oil, extracted from the outer layer of rice grains, is another option well suited to cooked dishes.

Beyond unsaturated fatty acids, rice bran oil contains trace compounds such as gamma-oryzanol, one of its most distinctive components. Researchers are actively studying gamma-oryzanol and its relationship to the oil's thermal stability.

Rice bran oil's other selling point is its taste — or rather, its lack of one. Its neutral aroma makes it easy to let ingredients speak for themselves, which is why it works particularly well in pan-fried and stir-fried dishes where the food's own flavor takes center stage.

Even so, "heat-stable" does not mean rice bran oil can be heated indefinitely. The composition of any oil changes with temperature and time. Oil is, ultimately, still oil.

A high smoke point is widely seen as the mark of a good cooking oil. The smoke point is the temperature at which an oil begins to visibly smoke, and the assumption follows that a higher smoke point means greater heat resistance and better health outcomes.

In reality, smoke point alone is not enough to determine whether a cooking oil is healthy. Thermal stability is shaped by a combination of factors: the type and composition of fatty acids, the presence of antioxidants, and the temperature and duration of heating. Recent research on the frying behavior of cooking oils has confirmed that degradation rates vary significantly depending on an oil's composition.

In short, the equation "high smoke point = healthiest oil" does not hold. What matters more in a home kitchen is simply not letting the oil get hot enough to smoke in the first place.