The chain reaction Initiation creates a lipid radical. Propagation reacts that radical with oxygen and other lipids, generating hydroperoxides. Termination occurs when radicals combine or are quenched. Hydroperoxides can then break down into aldehydes, ketones, acids, and many other products.

What speeds oxidation? Important factors include unsaturation, temperature, oxygen, light, trace metals, antioxidants, processing history, moisture, and food residues.

Antioxidants are system-dependent Tocopherols can interrupt radical reactions, but antioxidant effects depend on form, concentration, and interactions with other components. More is not always better.

What about health? Oxidized oils can contain reactive compounds with toxicological activity in experimental systems. That supports minimizing unnecessary degradation. Presence of a reactive compound does not, by itself, establish a specific human disease outcome at normal dietary exposure.

Everyday Lipid takeaway Protect oils from heat, light, oxygen, and metal contamination; avoid severe overheating; and remove badly degraded frying oil from service.

References - PMID: 34845958. - Liu X et al. Food Res Int. 2025. PMID: 39779163. - Zhao M et al. Food Res Int. 2025. PMID: 40022339.