Pre-20th century human populations exhibited prevalence rates of cardiovascular disease, obesity, and type 2 diabetes below 1–5%, coinciding with minimal consumption of industrially processed seed oils.

We analyzed the available evidence on pre-20th century rates of cardiovascular disease, obesity, and type 2 diabetes, along with dietary patterns including seed oil consumption. What we’ve found so far does not support the claim that these conditions were consistently below 1–5% in pre-industrial...