Is it the industrial processing that is the problem specifically? We have some super tasty cold pressed rapeseed in the UK.
Dunno about the processing. In terms of energy....and as it always tends, excess of it and obesity..
Polyunsaturated fats (pufas) are essential fatty acids. They are necessary in our diet as they provide fat molecules that our bodies cannot make.
There are pro inflammatory and anti inflammatory types. Veg oils are pro inflammatory.
They have an energy value but they are not easily metabolised for energy to do work. They are vital for various biological processes.
I don't know about the processing.. is a processed oil better or worse, for health, than its unprocessed form? Dunno.
So it is a matter of how much. And dunno about the precise or otherwise ratio.
But, nonetheless, there is the view that in excess, veg oils, and sugar and salt, is a driver for obesity, given they are prevalent in many cheap convenient fast energy dense foods.
But, it is one variable in a complex genetic, socio-economic multi layered disease process.
As a single variable, excess veg oil being inflammatory and due to calorie excess, are then stored (metabolising incurs energy cost and not necessary as there is plenty of energy around)....and so, in part, explains perhaps why obesity and inflammation are synonymous with each other.
However, the complex organic chemistry is beyond me but in seeking explanation, I've yet to see detailed breakdown of this view...and it is one which drives the view that veg oil is toxic. I'd add the caveat that only in excess but where the point is between excess calorie and excess pufas is hypothesised and not elegantly explained, yet or refuted, yet. Toxicity is dose dependent.
Rapeseed oil v butter?
In the context that all veg oils are toxic then butter wins.
In the context of someone who generally isn't stuffing doughnuts and fizzy drinks, rapeseed oil is really nice as a salad dressing.
Moderation. Again. Wins the day.
My view. Other views are available ?