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

Jan 19, 2026 2h 7m 32 insights
<p><a href="https://peterattiamd.com/laynenorton4/?utm_source=podcast-feed&amp;utm_medium=referral&amp;utm_campaign=260119-pod-laynenorton4&amp;utm_content=260119-pod-laynenorton4-podfeed"> View the Show Notes Page for This Episode</a></p> <p><a href="https://peterattiamd.com/subscribe/?utm_source=podcast-feed&amp;laynenorton4%20=referral&amp;utm_campaign=260119-pod-laynenorton4&amp;utm_content=260119-pod-laynenorton4-podfeed"> Become a Member to Receive Exclusive Content</a></p> <p><a href="https://peterattiamd.com/newsletter/?utm_source=podcast-feed&amp;utm_medium=referral&amp;utm_campaign=260119-pod-laynenorton4&amp;utm_content=260119-pod-laynenorton4-podfeed"> Sign Up to Receive Peter's Weekly Newsletter</a></p> <p>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.</p> <p><strong>We discuss:</strong></p> <ul type="disc"> <li>The idea behind this episode, biases, and evidence-based thinking [5:15];</li> <li>The four core arguments behind claims that seed oils are harmful [12:30];</li> <li>The Minnesota Coronary Experiment (MCE) [14:30];</li> <li>The differences among saturated, monounsaturated, polyunsaturated, and trans fats, and why those differences matter for cardiovascular disease [18:30];</li> <li>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];</li> <li>The Sydney Diet Heart Study (SDHS): an attempt to address the "duration problem" by enrolling a much higher-risk population [28:30];</li> <li>Debating whether evidence from randomized trials supports the idea that seed oils are uniquely harmful once major confounders are removed [34:00];</li> <li>The Rose Corn Oil trial: an often-cited study used to argue against polyunsaturated fats [36:30];</li> <li>Three studies where replacing saturated fat with polyunsaturated fat produced different results than earlier trials [41:30];</li> <li>Layne's explanation for why the evidence is pointing towards cardiovascular risk reduction when substituting polyunsaturated fat for saturated fat [47:30];</li> <li>What Mendelian randomization says about the causal role of LDL cholesterol in ASCVD [56:45];</li> <li>The compounding effects of life-long exposure to high LDL cholesterol [1:06:45];</li> <li>Does the linoleic acid (omega-6) content of seed oils cause inflammation? [1:13:45];</li> <li>Does the linoleic acid (omega-6) content of seed oils increase oxidized LDL? [1:19:30];</li> <li>Layne's analogy to explain why lower LDL particle number outweighs higher per-particle oxidation risk when comparing polyunsaturated fats to saturated fats [1:26:15];</li> <li>The role of oxidized LDL in CVD: exploring differences in a diet high in polyunsaturated fat (seed oils) versus high in saturated fat [1:28:00];</li> <li>Examining whether industrial processing and solvent extraction of seed oils—especially residual hexane—could plausibly cause long-term harm [1:34:00];</li> <li>The evolutionary and "ancestral diet" argument against seed oils [1:40:45];</li> <li>Weighing concerns about industrial processing of seed oils against the totality of metabolic and cardiovascular evidence [1:47:30];</li> <li>Practical considerations around dietary fats, cooking oils, and real-world food choices [1:50:00];</li> <li>Comparing the health impact of seed oils with that of caloric intake and activity levels, and how to prioritize interventions [2:00:15];</li> <li>More.</li> </ul> <p>Connect With Peter on <a href="https://twitter.com/PeterAttiaMD">Twitter</a>, <a href="https://www.instagram.com/peterattiamd/">Instagram</a>, <a href="https://www.facebook.com/peterattiamd/">Facebook</a> and <a href="https://www.youtube.com/channel/UC8kGsMa0LygSX9nkBcBH1Sg">YouTube</a></p>
Actionable Insights

1. Focus on Major Health Levers

Prioritize your health efforts on high-impact behaviors like managing caloric intake and increasing physical activity, rather than disproportionately worrying about minor dietary details like specific cooking oils.

2. Boost Strength and Activity

Prioritize improving your strength, lean mass, and overall activity levels (e.g., VO2 max, grip strength), as these are enormous predictors of longevity with massive impacts on mortality risk.

3. Monitor LDL and ApoB

Actively manage your LDL cholesterol and get your ApoB measured to ensure these critical markers of cardiovascular health are under control.

4. Manage All Cardio Risks

Recognize that cardiovascular health involves multiple interconnected factors beyond just LDL, including blood pressure, cardiovascular fitness, insulin sensitivity, and inflammation, and address them holistically.

5. Adapt Beliefs to Evidence

Be open to changing your deeply held beliefs and opinions when presented with new, compelling evidence, even if it contradicts your previous understanding or academic background.

6. Seek Converging Evidence

When assessing scientific claims, look for the overall consensus and converging lines of evidence from various study types to build stronger or weaker confidence in a statement’s accuracy.

7. Prioritize Net Health Outcomes

When evaluating health interventions or dietary components, prioritize the overall net effect on hard outcomes (like disease events) rather than getting fixated on individual mechanisms that might appear negative in isolation.

8. Reduce LDL Particle Count

Prioritize reducing the overall number of LDL particles (ApoB) in your bloodstream, as this is a more significant factor in preventing atherosclerosis than the individual oxidizability of each particle.

9. Prevent LDL Retention

To reduce oxidized LDL, focus on preventing LDL particles from penetrating and being retained within the arterial intima, as this is where most oxidation occurs.

10. Declare Personal Biases

Be upfront and vocal about your personal biases and beliefs, especially when they differ from consensus or evidence, to maintain transparency and intellectual honesty.

11. Beware Belief-Driven Bias

Be aware that personal beliefs can be as powerful, if not more powerful, than financial incentives in influencing adherence to evidence, especially in information-siloed social media environments.

12. Read Original Research

To accurately understand scientific findings, always read the original research paper rather than relying on headlines or social media summaries, which often misrepresent or oversimplify results.

13. Improve Overall Diet Quality

Recognize that negative health outcomes often stem from an overall low-quality diet high in ultra-processed foods (like chips and fries), rather than solely from the presence of seed oils.

14. Reduce Seed Oils, Cut Junk

Restricting seed oils can be beneficial by proxy, as it often leads to reducing consumption of low-quality, ultra-processed foods like chips and sugary dressings, but avoid being overly restrictive.

15. Limit Saturated Fat

If you choose to avoid seed oils, ensure you are still actively reducing saturated fat in your diet by opting for leaner cuts of meat and other lower saturated fat protein sources.

16. Replace Saturated Fat Wisely

When reducing saturated fat intake, consider substituting it with fiber-dense sources of carbohydrates, as this is likely to lead to a reduction in cardiovascular disease risk.

17. Opt for MUFAs

If you are concerned about seed oils, opt for monounsaturated fats like olive oil or avocado oil as a cardioprotective alternative to saturated fats.

18. Avoid Reused Frying Oil

Be aware that frying in thin layers of oil or reusing oil repeatedly, especially in restaurant settings, can quickly lead to the accumulation of oxidized and negative byproducts.

19. Beware ‘Health Washed’ Foods

Be critical of marketing claims that frame unhealthy foods (like fries) as ‘healthier’ due to specific ingredient changes (e.g., using lard instead of seed oils), as this can lead to overconsumption based on a false perception of health.

20. Consult Research Interpreters

Recognize that interpreting scientific research requires specific skills; seek out experts who can cut through the noise and provide accurate, contextualized information.

21. Enhance Debate Rigor

When engaging in debates or discussions, pre-submit all evidence and agree on source materials upfront, only referencing pre-submitted information to ensure rigor and prevent misinterpretation.

22. Word Carefully, Avoid Misinterpretation

When communicating complex information, especially in public forums, be extremely careful with wording to prevent misinterpretation, as audiences may draw incorrect conclusions.

23. Question Data Presentation

Understand that data can be selectively presented or analyzed to support a desired conclusion, so critically evaluate how data is framed and presented.

24. Respect Study Limitations

When evaluating research, acknowledge that all studies have limitations, and use this understanding to carefully interpret findings and avoid overgeneralization.

25. Grasp Longevity’s Evolution

Recognize that evolutionary biology prioritizes reproduction and genetic propagation, not necessarily maximum individual longevity, which explains why health declines after reproductive age.

26. Prioritize Evidence-Based Net Effect

When evaluating dietary components or health interventions, base your decisions on the overall net effect supported by the best available evidence, rather than relying on naturalistic or evolutionary arguments alone.

27. Disregard Trace Chemical Fears

Do not be overly concerned about trace amounts of processing chemicals like sodium hydroxide in refined oils, as the quantities are negligible and often chemically transformed, requiring impossibly large consumption to cause harm.

28. Moderate Seed Oil Use

Do not fear using seed oils like safflower or canola oil in moderation (e.g., in salad dressings) if you prefer their taste, as the data does not suggest significant harm in such contexts.

29. Address Beyond LDL

Even if LDL is pharmacologically controlled, continue to consider other health benefits and risks associated with dietary choices, such as the impact of frying oils on other health markers.

30. Restaurateurs: Drop ‘No Seed Oils’

If you are a restaurateur, remove ’no seed oils used’ claims from your menu, as this marketing is often based on misinformation and can be misleading to consumers.

31. Check Chemical Bioaccumulation

When evaluating the safety of trace chemicals in food, consider whether they bioaccumulate in the body or if the body can clear them quickly enough to prevent negative outcomes.

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