Science Vs: "Seed Oils: Should You Switch to Butter?"

Host: Wendy Zuckerman (Spotify Studios)
Date: November 6, 2025

Overview

This episode of Science Vs explores the rising controversy over vegetable (seed) oils and saturated fats. Host Wendy Zuckerman investigates the scientific evidence behind the new trend demonizing seed oils (canola, soybean, sunflower, etc.) and promoting butter and other saturated fats as healthful, guided by claims from Dr. Kate Shanahan and viral social media narratives. The core questions: Are seed oils really dangerous? Is butter back on the menu as a healthy choice? With expert interviews and deep dives into recent research, Wendy seeks clear answers rooted in science, not fads.

Key Discussion Points & Insights

1. Seed Oils Under Fire: The "Hateful Eight"

• Dr. Kate Shanahan's Claims (00:57–04:08):
  • Shanahan vehemently opposes mainstream nutrition, arguing that eight highly refined seed oils (soy, safflower, sunflower, corn, cottonseed, canola, rice bran, grapeseed) are extremely harmful.
    • “Avoiding vegetable oils is the most important action you can take to improve your health.” (02:17)
  • She attributes a wide array of diseases (from heart disease to cancer) to seed oils, claiming personal and patient experiences of miraculous recoveries when swapping seed oils for saturated fats.
    • Describes effects: “People who've done it feel better than ever... I had diabetes and I got off my diabetes medications in a weekend. I had heart failure. I no longer have heart failure.” (03:49)
• Social Buzz: The demonization is bolstered by online influencers who call seed oils “inflammatory”, “poisons,” and “of the devil.” (04:22–04:45)

2. Revisiting Saturated Fat: Is Butter Really Bad?

• Historical Sidelining of Saturated Fat (06:44–08:29):

  • The show flashes back to the 1980s-90s diet culture: saturated fat (in butter, bacon, cream) was universally maligned due to its role in raising cholesterol.
  • “Saturated fat can clog this pipe. Imagine what it’s doing to yours.” (UK health ad, 08:01)

• Expert View: Jason Wu, Nutrition Scientist (08:29–13:10):

  • Wu describes how evidence linking saturated fat to heart disease emerged from 1950s epidemiology, but more recent studies complicate that story.
    • “The story is not as simple as what it seemed.” (09:24)
  • Wu’s large meta-analysis (600,000+ people, 10,000 heart disease cases):
    • Eating butter daily slightly increases premature death risk (by just 1%)—a “barely statistically significant” result.
    • “Absolutely no relationship between eating more butter and heart disease risk.” (11:38)
    • Slightly lower risk of type 2 diabetes (by 4%) for butter eaters, but much smaller than risks from sugary drinks.
  • Conclusion: Butter is not a health food—but not a “big killer” either.

• Nuanced View:

  • While some reviews show cutting back on saturated fat slightly reduces heart disease risk, the overall effect is modest.
    • “Saturated fat is not the big killer that the 80s led us to believe.” (12:55)
  • Wu cautions: “We basically found a somewhat neutral to marginal effect of butter.” (21:47)
  • Saturated fat may increase LDL ('bad') cholesterol, but many other factors (genes, nutrients in butter, type of cholesterol) matter.

3. Cholesterol: Villain or Vital? (14:34–21:39)

• David Shade, Endocrinology Professor:

  • “Cholesterol is absolutely critical... Otherwise we’d all be a pile of Jello.” (15:33)
  • Explains cholesterol’s essentials (cell structure, hormone synthesis) and why excess LDL is problematic: small LDL particles sneak into artery linings, leading to dangerous build-ups ("plaque") and possible heart attacks.

• The LDL/Saturated Fat Puzzle:

  • Diets high in saturated fat do raise LDL cholesterol (18:07). Even Dr. Shanahan’s cholesterol “went through the roof” on such a diet (18:07).
    • “My cholesterol levels have gone through the roof since I started this.” – Dr. Shanahan (18:07)
  • Yet, if LDL and saturated fat are up, why isn’t heart disease risk clear-cut? Shade explains LDL is just “about a 1% player out of the whole 100% field”—other factors (genes, smoking, blood pressure) are much more significant (18:52).
  • Saturated fat tends to increase less harmful, larger LDL particles; minor nutrient benefits may offset some risk.

4. Seed Oils and Disease: Is There Evidence? (25:14–39:11)

• Dr. Shanahan’s Theory:

  • Increasing seed oil consumption in the US correlates with rising chronic diseases. She believes biochemistry and animal studies suggest seed oils cause inflammation via “dangerous particles” and free radicals (26:26–28:08).
    • Lists diseases she links to seed oils: “skin conditions like acne and eczema...cancer, dementia, Parkinson’s, heart attacks...there’s nothing that won’t get better when you stop eating seed oils.” (26:52)

• Testing the Claims: Experimental Evidence

  • David Egman’s Muffin Studies (29:07–30:28):

    • Ran randomized trials feeding people muffins baked with either palm oil (saturated fat) or sunflower oil (seed oil). After eight weeks, “no increases in inflammation” found in the seed oil group (30:25–30:28).
    • Large systematic reviews echo: “virtually no evidence that adding seed oils to your diet bumps up your inflammatory markers.” (30:28)

  • Critiques from Dr. Shanahan:

    • She argues studies are too short and only measure “markers,” not real clinical disease (30:44–31:12).

  • The "Buttock Fat" Study (31:12–33:47):

    • Egman's team examined long-term fat stores in the body (“buttock fat”) of Swedish men:
      • Those with more polyunsaturated fats from seed oils stored in body fat had a lower risk of dying.
      • “If you have more of this in your buttock fat...then you lived longer.” (33:14)
    • Dr. Shanahan: “That doesn’t make any sense...that does contradict my theory.” (33:49–33:56)

  • Wider Context:

    • Most large reviews (inc. a 24,000-person meta-analysis) suggest swapping saturated fat for seed oils reduces heart disease risk. (34:20–36:02)
      • “The evidence are pretty consistent…replacement of saturated fat with polyunsaturated fat does reduce the risk of cardiovascular disease.” – Jason Wu (35:58)
    • Dr. Shanahan dismisses the bulk of evidence, focusing on a minority of studies that support her view.

5. Summing Up: Seed Oil Theory vs. Mainstream Science

• Host’s Reflection (38:19–39:15):

  • Shanahan trusts a “few” studies showing harm, dismisses many showing safety/benefit.
  • Personal anecdotes (e.g., celebrity deaths) used as support are not evidence.
  • Junk food is unhealthy regardless of fat type; removing seed oils and eating more whole foods may help, but not necessarily because of seed oils.

• Final Verdict (David Shade):

  • “Every year, there are crazy diets that people put out without any scientific justification, and that’s one of them. It’s all crapola.” (40:23)
  • “Crapola is how you say crapola.” – Wendy Zuckerman (40:33)

Notable Quotes & Memorable Moments

• On Dogma vs. Evidence:
  • “Medical science is messed up when it comes to nutrition.” – Dr. Kate Shanahan (00:57)
• On Butter & Disease:
  • “Absolutely no relationship between eating more butter and heart disease risk.” – Jason Wu (11:38)
  • “We basically found a somewhat neutral to marginal effect of butter.” – Jason Wu (21:47)
• On Biochemistry & Paradigm Shifts:
  • “Really, what’s needed for any paradigm shift is a wholesale restructuring of the way we approach a problem...Paradigm shifts are difficult.” – Dr. Kate Shanahan (37:43)
• On the State of Seed Oil Science:
  • “Replacement of saturated fat with polyunsaturated fat does reduce the risk of cardiovascular disease.” – Jason Wu (35:58)
• On Fads and Science:
  • “It’s all crapola. Crapola is how you say crapola.” – David Shade, Wendy Zuckerman (40:23–40:35)

Timestamps by Key Segments

| Timestamp | Segment / Discussion | |-----------|------------------------------------------------------------------------------------------------------------| | 00:00 | Introduction and rise of the anti-seed oil trend; Dr. Kate Shanahan interview | | 04:45 | Explosive social media rhetoric against seed oils | | 06:44 | History of saturated fat guidelines in the 80s-90s | | 08:29 | Jason Wu: reassessing evidence on saturated fat and butter | | 11:38 | “No relationship between eating more butter and heart disease risk” – Jason Wu | | 14:34 | Conversation with David Shade: What is cholesterol? | | 18:07 | Case studies of skyrocketing LDL cholesterol on high saturated fat diets | | 21:47 | “Neutral to marginal effect of butter” – nuanced message around saturated fat | | 25:14 | Focus shifts to seed oils; Dr. Shanahan’s theory on disease rise | | 29:07 | Muffin study: randomized trial on inflammation and seed oils | | 33:14 | Buttock fat study: higher seed oil consumption linked to longer life | | 34:20 | Big-picture review: evidence consistently shows seed oils reduce risk vs. saturated fats | | 38:19 | Dr. Shanahan on why she ignores most of the evidence | | 40:23 | David Shade’s “crapola” dismissal of fad diets |

Tone & Style

Wendy Zuckerman’s tone is witty, playful, and scientifically rigorous. She brings both skepticism and openness as she explores claims, pokes fun at diet dogmas, and persistently chases down evidence.

Conclusion

Science Vs concludes that the mainstream, evidence-based view still holds:

• Saturated fat (like butter) is not the dietary villain it was once made out to be, but also not a health elixir.
• Seed oils do not show evidence of being intrinsically harmful or more “inflammatory” than other fats, and large studies suggest that substituting them for saturated fats generally improves cardiovascular health.
• The anti-seed oil movement relies more on theory and anecdote than robust evidence.
• As always, context, overall diet quality, and moderation matter most—ignore the fads, trust the weight of the evidence, and pass (or keep) the butter if you like, but no need to fear your canola oil bottle.

For citations, in-depth studies, and further reading, see the episode’s show notes and transcript links.