Every ten years or so there's a new batch of evidence that eating a lot of something has some health effects for some folks. Then a minority turns it into a morality cult against the thing and the media picks it up as "you woudn't guess what common food could be killing you"

And then ten years later new evidence for that thing comes out that's like "maybe not so bad after all!" and a new set of backlash morality. These things are politically affiliated now too if they can be depending on who picks up which evidence first.

Each decade people get bored and find something new to be upset about.

"gluten" is definitely way down these days and "seed oils" haven't yet hit their peak.