"Life expectancy has doubled since 1900, so clearly modern food is working."
Yes. Brilliant point. Absolutely watertight.
Tell me, when you picture a Victorian dying at thirty-eight, what do you think killed him?
Was it the butter on his bread?
Was it the lard in the pan?
Was it the grass-fed mutton? The eggs from the yard? The unpasteurised milk straight from the cow he could see from the kitchen window?
Or was it cholera, tuberculosis, dysentery, smallpox, sepsis from a splinter, childbirth in a room with no soap, a boiler explosion, a coal mine, a war, a workhouse, and the entirely reasonable medical practice of being bled by a man with a leech?
We did not extend life expectancy by replacing his lard with sunflower oil.
We extended it by inventing the toilet, the antibiotic, and the idea that surgeons might wash their hands occasionally.
The margarine is doing nothing. The margarine is, if anything, slightly working against the project.
The plumbing did the heavy lifting. Give the plumber a statue.