This makes perfect sense, given that fatty acids become more susceptible to oxidation (accelerated by heat, light and air exposure) the more unsaturated they are. One can very, very roughly think of the increase in susceptibility as increasing an order of magnitude moving from saturated->monounsaturated->polyunsaturated, though the exact amount will vary depending on the particular fatty acid. Rustic survival foods with long ambient temperature "shelf" life such as pemmican was generally made with fat from ruminants, which is generally very saturated (compared to monogastric animals like pigs and chickens, who tend to bioaccumulate polyunsaturated fats from their feed). The best fat to use was basically the saturated hard wax found near the kidneys of bison, which could last many months before going rancid (oxidized)
When things like polyunsaturated fatty acids degrade, they release free radicals, lipid peroxides and other toxic compounds like aldehydes (which are known to be cytotoxic and genotoxic), and it seems very plausible that these things could be outright carcinogenic, or force cells to spend their resources cleaning up this additional load instead of repairing or protecting DNA after damaging sun exposure.
If all of that is true, then you have to answer for why "seed oils" improve human health outcomes in RCTs.
Here's Layne Norton making this point yesterday in response to Huberman in a Twitter thread you should read: https://twitter.com/BioLayne/status/1704477570417254530. He lists some of these interesting RCTs as well, but here's the summary:
> If you only look at epidemiology & in vitro/mechanistic data you can hack together a horror story for almost any nutrient
> In RCTs where n-6 PUFAs (aka seed oils) are used in place of SFA there are neutral/positive effects on health
You can speculate all day about how bad certain mechanisms like oxidation or compounds like phytates might be for us. But why would that be convincing to you when these foods, whether it be seed oils or legumes (which have phytates for example), improve human health outcomes in the highest tier of evidence?
There's a reason why "seed oil disrespecters" on social media hang around the lowest tier of evidence like Ray Peat'ian narratives and mechanistic speculation rather than stick to RCTs and metaanalyses.
When things like polyunsaturated fatty acids degrade, they release free radicals, lipid peroxides and other toxic compounds like aldehydes (which are known to be cytotoxic and genotoxic), and it seems very plausible that these things could be outright carcinogenic, or force cells to spend their resources cleaning up this additional load instead of repairing or protecting DNA after damaging sun exposure.