What antioxidants break chain initiation and which break chain propagation?

[Alex K Chen]

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Now, vitamin E is known as a chain-breaking antioxidant. Contrary to the assertions of Fleetwood Mac, you can break the chain reaction with vitamin E. However, vitamin E does not break the initiation part. It breaks the propagation step. And the reason is that vitamin E is 1000 times more reactive towards lipid peroxyl radicals than other PUFAs are. And so, if you have enough vitamin E in the cell membrane, you will break the chain, and you'll stop the propagation step. But you can't do anything to stop the initiation reaction because vitamin E is situated in the membrane. Both its position in the membrane and its reactivity prevent it from stopping a water-soluble oxidant from reaching the edge of the membrane and oxidizing a new PUFA.

It is only is good at stopping lipid peroxyl radicals from oxidizing other PUFAs in the cell membrane. So, what that means is that your production of oxidants, your water-soluble antioxidant protection and having the right amount of PUFA in the cell membrane cannot be replaced by having vitamin E. And what that means is that you do need more vitamin E when you have more PUFA, but vitamin E can never, ever, ever, ever, ever, ever, ever protect you against consuming too much PUFA. And so, you want the right amount of PUFA, but you don't want any more than that in your cell membranes because if it is increasing in the cell membrane in response to diet beyond its utility, all it's doing is providing an oxidative liability.