Podcast Summary: "Why you don't need to avoid seed oils"

Podcast: What's That Rash?
Host(s): Norman Swan, Dr. Sarah Berry
Date: January 6, 2026
Episode Theme: Debunking myths about seed oils and evaluating their impact on health.

Episode Overview

This episode tackles the rising concerns around seed oils, prompted by public figures like Robert F. Kennedy Jr., who claim seed oils are harmful and advocate for a return to animal fats. Host Dr. Sarah Berry and Norman Swan respond to a listener question, dissect the biochemistry, and discuss the evidence for and against seed oils in the diet. Their goal: to clarify whether avoiding seed oils is necessary and to give listeners the "good oil" on the topic.

Key Discussion Points & Insights

1. What Are Seed Oils?

• Definition: Oils pressed or manufactured from seeds—sunflower, flax, sesame, peanut, canola, rice bran, etc. (02:11)
• Clarification: Olive oil is not a seed oil; it comes from the fruit, not the seed.

2. Seed Oils and the Paleo Diet Myth

• The notion that seed oils are "new" is a misconception; seeds have long been a part of human and pre-human diets. (03:18)
• Paleo fantasies romanticize hunter-gatherer diets, but humans have always adapted to their environment and foods, including seeds and complex carbohydrates.
• Quote:
  "Seeds have been part of human diets for, well, hominid diets for millions of years."
  — Dr. Sarah Berry [03:52]

3. Types of Fats in Oils

• Saturated Fats: Generally considered unhealthy, often found in animal fats.
• Monounsaturated Fats: Neutral effect on cholesterol; present in olive oil.
• Polyunsaturated Fats: Includes omega-3 and omega-6 fatty acids; these are essential and must come from diet.
• Quote:
  "We've got fats surrounding our cells to keep the integrity of our cells together... and communication between cells involves fats as well."
  — Norman Swan [05:34]

4. Omega-6 vs. Omega-3: The Ratio Debate

• Many seed oils contain more omega-6 than omega-3, fueling worries about an “unhealthy” imbalance.
• The "omega-6 to omega-3 ratio is bad" idea stems from older, largely debunked research.
• New evidence shows both omega-3 and omega-6 are beneficial; omega-6s are linked to lower heart disease and inflammation rates.
• Quote:
  "Omega 6 fatty acids have been wrongly labeled as bad for you. They're not bad for you. There's almost no evidence for that."
  — Norman Swan [08:27]

5. Seed Oils, Animal Fats, and Health Claims

• Claims like those from RFK Jr., that seed oils are "poison," are not based on solid evidence.
• Calls to return to animal fats overlook their high saturated fat content and associated negative health effects.
• Comparisons to groups like the Amish (who eat more animal fats) ignore their much higher activity levels and lifestyle differences.
• Quote:
  "Life expectancy in the paleolithic was about 28. So just be careful what you wish for here."
  — Norman Swan [10:19]

6. Benefits of Polyunsaturated (Seed) Oils

• Polyunsaturated fatty acids (PUFAs, e.g., omega-6 and omega-3) lower LDL ("bad") cholesterol and may reduce type 2 diabetes risk. (11:58)
• Linoleic acid, a PUFA found in many seed oils, is essential; deficiency can cause skin problems.
• The main health benefit of olive oil comes from replacing saturated fat, not necessarily from its monounsaturated fat content.

7. Seed Oils in Ultra-Processed Foods

• While seed oils are common in ultra-processed foods due to their price and stability, they're not inherently harmful—overconsumption and overall calorie load matter more.
• Most critics focus on the biochemistry of the oils, not their role in processed foods.
• Concerns about seed oil byproducts like arachidonic acid are unfounded; only a tiny fraction of linoleic acid converts to it. (13:21)

8. Evidence Against Seed Oils: Is There Any?

• No strong evidence supports claims that seed oils are harmful when consumed as part of a balanced diet.
• Epidemiological, metabolic, and lab studies support beneficial effects of seed oils on cholesterol and possibly diabetes risk.
• Quote:
  "I haven't really heard any strong evidence against seed oils. Norman, is there something that I've missed here?"
  — Dr. Sarah Berry [13:42]
  "Not that I can find...they all point in the same direction in terms of a beneficial effect."
  — Norman Swan [13:54]

9. Practical Advice for Listeners

• Seed oils are safe to use for cooking and frying in moderation.
• Avoid reusing oil multiple times at high heat, as repeated heating can cause chemical changes. (15:13)
• The key health risks come from excess fried foods/calories, not the seed oil itself.
• Quote:
  "It's the fried foods and the calories that you should be worried about far more. But you should not be reusing seed oils more than once."
  — Norman Swan [15:13]

Notable Quotes & Memorable Moments

• Paleo Fantasies:
  "Humans have never lived in harmony with nature, we're constantly adapting to it. That's what evolution means."
  — Dr. Sarah Berry [03:24]

• On Olive Oil's Benefits:
  "It's that replacement that gives you most of the benefit when you're eating monounsaturated fats."
  — Norman Swan [11:10]

• Norman's Glasgow Childhood:
  "When I was a child, my mother had a chip pan on the stove the whole time and that oil was never changed."
  — Norman Swan [15:52]
  "Don't grow up in Glasgow."
  — Norman Swan [15:54]

• Hosts' Banter:
  "I do love the rebrand that you've managed to pull off here, Norman, by being a boy eating chips in Glasgow to being the ding ding diet toting health guru that you are today."
  — Dr. Sarah Berry [15:56]

Timestamps for Important Segments

• Seed oils defined: [02:11]
• Paleo diet discussion: [03:11]–[04:22]
• Types of dietary fats explained: [04:47]–[06:26]
• Omega-6/Omega-3 ratio debate: [06:41]–[08:27]
• Addressing RFK Jr.’s claims: [09:01]
• Olive oil benefits explained: [10:37]–[11:58]
• Ultra-processed foods and seed oils: [12:09]–[13:21]
• Lack of evidence for harm: [13:42]–[14:26]
• Practical advice on oil use: [15:01]–[15:54]

Conclusion

Bottom Line:
There is no credible evidence that seed oils are harmful when consumed in a balanced diet. Both omega-6 and omega-3 fatty acids are important and beneficial. The main health concerns come from overconsumption of calories and fried foods, not seed oils themselves. Use seed oils responsibly, avoid excessive reuse, and focus more on overall diet quality than on avoiding particular oils.

Final Words:
“If he's using seed oils responsibly ... it's fine. It's the fried foods and the calories that you should be worried about far more."
— Norman Swan [15:13]