#380 ‒ The seed oil debate: are they uniquely harmful relative to other dietary fats? | Layne Norton, Ph.D.

View the Show Notes Page for This Episode Become a Member to Receive Exclusive Content Sign Up to Receive Peter's Weekly Newsletter Layne Norton is a nutrition scientist and accomplished power athlete,who returns to The Drive for a conversation that departs from the show's usual format. In this episode, Layne presents the evidence-based case that seed oils are not uniquely harmful under isocaloric conditions, while Peter steelmans the strongest versions of the opposing argument that seed oils are inherently harmful. They examine how scientific bias and evidence are evaluated, revisit the historical randomized controlled trials that shaped the seed oil controversy, and explore the mechanistic biology underlying LDL oxidation and atherosclerosis. Along the way, Layne unpacks the chemistry and processing of modern seed oils, assesses evolutionary and ancestral nutrition arguments, clarifies the relationship between seed oils, ultra-processed foods, and contemporary dietary patterns, and situates these questions within the larger context of lifestyle factors that drive cardiometabolic health. Layne concludes by offering practical considerations around dietary fats, cooking oils, and real-world food choices. We discuss: The idea behind this episode, biases, and evidence-based thinking [5:15]; The four core arguments behind claims that seed oils are harmful [12:30]; The Minnesota Coronary Experiment (MCE) [14:30]; The differences among saturated, monounsaturated, polyunsaturated, and trans fats, and why those differences matter for cardiovascular disease [18:30]; Missing trans fat data as a confounder in the Minnesota Coronary Experiment, other limitations of that study, and the challenge detecting meaningful differences in hard outcomes through nutrition research [24:00]; The Sydney Diet Heart Study (SDHS): an attempt to address the "duration problem" by enrolling a much higher-risk population [28:30]; Debating whether evidence from randomized trials supports the idea