Trans fats are a good example of this. They used to be the prime replacement for saturated fats. Now, in the US, they are effectively banned.
This hit oreos. [1]
[1] https://www.orlandosentinel.com/2006/01/02/manufacturers-tri...
The fracking industry has made guar gum too expensive to use as a food emulsifier. I know someone who reacts to xanthan gum (which has all but replaced guar) and she's not a happy camper, because it's in fucking everything.
Palm oil is thick at room temp, like partially hydrogenated oils are.
They did use lard till mid 90s.
https://news.cornell.edu/stories/2008/02/getting-lard-out-ko...