There's always a new villain to explain why people are so fat, because people don't want to accept the obvious answer. Previous villain was corn syrup, you hear about that less these days. New villain is seed oils. Similar lack of evidence for either being worse than their "healthy" alternative (normal sugar or other fats). Check back in 5 years and there will be another villain.

I've seen it discussed on Twitter for a while, mostly on the right. As best I can tell it is related to a general trend toward distrust of big agriculture, big pharma, big institutions in general as seed oils are painted as a product of that whereas animal fats are a "retvrn" type of diet (or from another POV, a Michael Pollan diet). Funny to see the political factions shifting around and the horseshoe connecting left and right on nutrition.

Seed oils are part of RFK's agenda, he doesn't like them. I'm not sure that position is informed by facts though. He recently did a publicity stunt with a restaurant that replaced their fry oil with beef tallow.

MAGA is against mRNA, seed oils, and all sorts of random stuff because a random higher up in their movement said so. This is generally without evidence.

It's been building for decades in alternative health circles.

There's legitimate science about them dating back to the late 80s/early 90s.

In 1999 Sally Fallon published a book called Nourishing Traditions which argued for rejecting modern industrial foods. A lot of the arguments you see today about seed oils originate from this book.

These got amplified in 2014 by Nina Teicholz who published a book called The Big Fat Surprise which made it the topic de jure of alternative health influencers.

Then it's been a steady build across social media for about a decade.

I think the source is that years and years ago someone plotted seed oil consumption and heart disease on a graph, probably attempting to show a correlation. And now we've got claims of causation.

Much like you I too have just woken up from under my rock to find this out. On the bright side it seems we didn't miss anything so as you were.