This is false, in the 90s when I grew up there was no such criterion, and the posters of the pyramid prominently depicted sliced white bread.
The worst part of the food pyramid was the indication to use all fats and oils sparingly. There's never been any point in which the evidence suggested that olive oil or other monounsaturated fats should be avoided
Agree that the wholesale demonisation of fats was a massive failure of policy. Doubly frustrating because this was known - Ancel Keys' hypothesis was always about saturated fat specifically, and the Keys equation he devised showed the beneficial effects of PUFA. So mainstream nutrition science was on the money, but policy makers and companies less so.
This is false, in the 90s when I grew up there was no such criterion, and the posters of the pyramid prominently depicted sliced white bread.
The worst part of the food pyramid was the indication to use all fats and oils sparingly. There's never been any point in which the evidence suggested that olive oil or other monounsaturated fats should be avoided