As long as we're off topic outside the galaxy, here's an article authored by a neurosurgeon explaining the benefits of a couple of polyunsaturated fats which are found in high concentrations in the brain. Merely because a molecule contains conjugated ethylenic linkages does not mean the body will quickly turn those linkages into peroxidated forms, there is much more going on in the body, so blanket statements like the one you'd writ should be scrutinized a little better. There are a lot of molecules in the body that are not very stable outside its environment but that's not really important, what is important is sometimes knowing what they are, this enables a clue to theorize what might be happening. It is a normal part of metabolic energy production for oxygen to add to those ethylenics. Here's the article, I bet the audience will find it interesting and I apologize for going off topic but couldn't resist refuting your statements, I wish this stuff were that simple.
Here's a quote from Blaylock's article, concerning those dangerous unstable polyunsaturated fats known as EPA and DHA: "Some 70% of energy supply during fetal development is devoted to brain development, and lipids make up 50 to 60% of the structure of the brain, with DHA making up 30% of the brain and 50% of the retina’s structure."