TLDR: Nothing burger junk science paper we see pumped out every 3 months from the same observational food frequency questionnaires.
Findings In this cohort study of 221 054 adults from 3 large cohorts, higher butter intake was associated with increased total and cancer mortality, while higher intake of plant-based oils was associated with lower total, cancer, and cardiovascular disease mortality.
Meaning Substituting butter with plant-based oils, particularly olive, soybean, and canola oils, may confer substantial benefits for preventing premature deaths.
Conclusions and Relevance In this cohort study, higher intake of butter was associated with increased mortality, while higher plant-based oils intake was associated with lower mortality. Substituting butter with plant-based oils may confer substantial benefits for preventing premature deaths.
Full paper: https://doi.org/10.1001/jamainternmed.2025.0205
Whooh, lots to unpack here.
So the normal horsemen of weak science, tiny hazard ratios, low probability associations, relative risk only, observational, cohorts, food frequency questionaries, not clinically significant.
evidence pyramid
This is observational, which is hypothesis generating, not showing causation. We have healthy patient confounders, sugar and fructose confounders, etc.
So every FOUR years people were asked to categorize what they had eaten in the last 4 years....
They didn't like the data... so they reclassified people posthoc.
Major Issue: These FFQs don't take into account metabolic health. People on a Ketogenic LCHF, or a Zero Carb (Carnivore) diet absolutely do not have increased mortality. These FFQs can be sliced to show any association that you like, the fact they are mixing healthy patients (following guidelines) with people who don't follow any guidelines (including alcohol, sugar, fructose, etc) and seeing a overall health benefit from the guideline followers doesn't meat every single association is causative.
The Standard American Diet (SAD) is so absolutely BAD that any intervention looks good compared to it. Sadly a major component of the SAD diet is seed oils, which this paper is trying to promote. If they wanted to do real science they would hold seed oils constant in a study and add real butter on top, or have a 100% ASF fat diet vs 100% Seed oil diet (oh wait, we did that study already, they didn't like the data and hid it for 30 years - spoiler seed oils kill people)