Sunflower oil's hidden dangers: Why it's bad for frying

Do you know which oil to use for frying? Many people ponder the choice of the appropriate fat, especially when standing in front of a store shelf filled with various oils.

Sunflower oil is one of the most popular oils used in the kitchen, right after canola oil. It is an essential ingredient in many dishes, often used for frying and baking. Unfortunately, this is not a beneficial practice.

Sunflower oil (as well as soybean, corn, grape seed, pumpkin seed, and sesame) contains a predominant amount of polyunsaturated fatty acids, which quickly oxidize under high temperatures. This means that during frying, the polyunsaturated fatty acids in sunflower oil break down into harmful substances, including those with potentially carcinogenic properties.

Moreover, scientists from De Montfort University and Oxford scholars indicate that heated sunflower oil may release carcinogenic aldehyde. Therefore, it is better to use sunflower oil raw (e.g., in salads) and not recommended for frying.

For home frying, oils that contain a lot of monounsaturated fatty acids (MUFA) and few polyunsaturated fatty acids (PUFA) are best. Examples of such oils include canola oil and olive oil. Monounsaturated fatty acids are more resistant to oxidation under high temperatures. Because canola oil contains about 61% monounsaturated fatty acids and 29% polyunsaturated fatty acids, it is suitable for both short-term frying and salads.

Most oils available in stores are sold in plastic bottles. These are usually refined oils, meaning they have been purified at high temperatures (over 320°F) and using chemicals. This process removes impurities but also strips away important components. In theory, refined oils can be used for frying because they have a higher smoke point. However, it is still better to fry with refined canola oil than with refined sunflower oil. As mentioned, sunflower oil still contains more polyunsaturated fatty acids, which have an unfavorable fatty acid profile for frying.

"Refining oil does not make it suitable for frying; it only raises its smoke point, which is beneficial for oils with a good fatty acid profile for frying — for example, canola oil or peanut oil," explains nutritionist Aleksandra Kureń on the centrumrespo.pl website.