Why some oils smoke and get yucky when you cook with them
Impact of Heating Temperature and Fatty Acid Type on the Formation of Lipid Oxidation Products During Thermal Processing
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When you heat oils, they break down and make chemicals that might be bad for you. Oils with lots of double bonds (like soybean oil) break down faster and make more of these chemicals than oils with fewer double bonds (like olive or lard oil).
Surprising Findings
4-HHE — a highly toxic aldehyde — was ONLY found in oils containing linolenic acid (soybean oil), and nowhere else.
People assume all oils produce similar toxins when heated. But this shows some toxins are exclusive to specific fatty acids — meaning soybean oil has a unique danger profile.
Practical Takeaways
Use olive oil for low-heat cooking (<180°C) and animal fats (lard, tallow) or coconut oil for high-heat frying — avoid soybean oil entirely for frying.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When you heat oils, they break down and make chemicals that might be bad for you. Oils with lots of double bonds (like soybean oil) break down faster and make more of these chemicals than oils with fewer double bonds (like olive or lard oil).
Surprising Findings
4-HHE — a highly toxic aldehyde — was ONLY found in oils containing linolenic acid (soybean oil), and nowhere else.
People assume all oils produce similar toxins when heated. But this shows some toxins are exclusive to specific fatty acids — meaning soybean oil has a unique danger profile.
Practical Takeaways
Use olive oil for low-heat cooking (<180°C) and animal fats (lard, tallow) or coconut oil for high-heat frying — avoid soybean oil entirely for frying.
Publication
Journal
Frontiers in Nutrition
Year
2022
Authors
Zhuang Yuan, Jun Dong, Xiaomei He, Junping Wang, Changmo Li, Lu Dong, Yan Zhang, Xiaofei Zhou, Hongxun Wang, Yang Yi, Shuo Wang
Related Content
Claims (10)
When you cook oils at high heat, especially above 180°C, they break down and make more harmful chemicals — the hotter it gets, the more chemicals form.
Oils with lots of unsaturated fats, like soybean oil, produce way more toxic chemicals when heated to frying temperatures than oils with more saturated fats.
Olive oil’s polyunsaturated fat content (11%) renders it more susceptible to thermal oxidation than animal fats with lower PUFA content (e.g., tallow, ghee <2%).
Oils with polyunsaturated fatty acid content exceeding 10% are susceptible to thermal oxidation during cooking, generating harmful aldehydes and polar compounds even below smoke point.
The more linolenic acid (a type of omega-3) an oil has, the more MDA and 4-HHE it makes when heated — these chemicals only show up in oils with this specific fat.