Fresh Air "Best Of: Nutritionist Marion Nestle / Science Writer Mary Roach"

Date: November 29, 2025
Hosts: Tonya Mosley, Terry Gross
Guests: Marion Nestle, Mary Roach

Episode Overview

This "Best Of" episode of Fresh Air features two in-depth interviews:

• Leading nutrition and food policy expert Marion Nestle, who discusses the evolving landscape of the American food system, food marketing, public health, and her latest book, What to Eat Now.
• Popular science author Mary Roach, whose new book, Replaceable You, explores the latest breakthroughs and questions in organ transplants, prosthetics, and body part replacements, mixing science, humor, and curiosity.

Segment 1: Marion Nestle on Food Policy and Industry

[00:57] Introduction to Marion Nestle

• Background: Molecular biologist, influential food policy scholar, author of What to Eat, Safe: The Politics of Food Safety, and more.
• New book, What to Eat Now, examines today’s supermarket, ultra-processed foods, and changing dynamics due to tech and policy.
• Noted for guiding Americans through food industry tactics and political influence.

[04:24] The RFK Administration and Food Policy

• Tonya Mosley: Invites Nestle to reflect on RFK Jr.’s leadership and food reform agenda.

• Marion Nestle: Initially hopeful about the focus on “toxins out of the food supply” and tackling ultra-processed foods.

  “When President Trump introduced his nomination of Robert F. Kennedy, Jr. on social media... I nearly fell off my chair. I thought, here's the president sounding just like me. What's going on here?” – Marion Nestle [05:22]

• Disappointment as subsequent reports and reforms pulled key initiatives.

  “They had backed off on nearly all of the things I thought were critically important.” – Marion Nestle [06:05]

[06:17] Key Food Policy Issues Dropped

• Points Nestle felt were ignored:

  • Curbing marketing to children
  • Reducing ultra-processed foods
  • Cleaning up school food
  • Removing toxins at the production level

• Criticizes “MAHA wins” (superficial industry pledges):

  “Froot Loops with vegetable dyes are still Froot Loops. It’s not going to make a big difference... Coca-Cola substituting cane sugar for high-fructose corn syrup, something that I termed nutritionally hilarious...” – Marion Nestle [08:12]

• Needs real structural reform: agricultural subsidies, marketing restrictions, universal and quality school meals, and public policy shifts.

[09:50] Why Promising Initiatives Fizzle: The Power of Lobbying

• Nestle explains how industry and agricultural lobbying dilute or remove meaningful public health measures.
  • Lobbying brings threats of job losses, moving overseas, and profit loss.
  • “That’s what always happens.” [10:14]

[10:35] The Compartmentalized Approach to Public Health

• Observes that food, medicine, and vaccines get siloed; public policy isn’t holistic due to industry interests and ideological divides.

  “We're in an era in which science is just considered just one way of looking at things and people have different sets of facts that they believe. And this is part of food politics now in a way that's very troubling.” – Marion Nestle [11:34]

[13:06] Supermarkets: The Business of Selling, Not Nutrition

• Methodology for What to Eat Now combines investigative journalism and hands-on store visits.

• Supermarkets exist to maximize sales and profits—not public health.

• “Slotting fees”—companies pay for prime shelf space, keeping out small producers.

  “Slotting fees are payments that food companies make to grocery stores to stock their products where people will see them... By the inch of space.” – Marion Nestle [14:02]

  “The purpose... is to sell as much food as possible to as many people as possible, as often as possible, at as high a price as they can get away with. I can't say that enough.” – Marion Nestle [16:46]

[17:17] Three Key Food System Shifts (2006–2025)

1. Food System Changes
2. Ultra-Processed Foods
3. Triple Duty Diets

Ultra-Processed Foods

• Origin: Coined by Brazil’s Carlos Monteiro; industrially produced with additives, bear little resemblance to original whole foods.

• Associated with poor health outcomes—supported by trials showing increased calorie intake.

  • Example: Corn on the cob (unprocessed) vs. canned corn (processed) vs. Doritos (ultra-processed).

  “Dorit are ultra processed. Mmm, mm.” – Marion Nestle [18:52]

• Designed to be irresistible: “You can’t eat just one.” [19:14]

Environmental Impact

• Ultra-processed foods cause up to a third of food-related environmental harm in wealthy nations.

  • Packaging waste, energy, and ingredient processing increase footprint.
  • The food system is geared toward animal feed and ethanol, not direct food for people.

  “We don't have a food system that's aimed at producing food for people. We have a food system that's aimed at producing feed for animals and fuel for automobiles. But the emphasis on animals is not very good for our environment...” – Marion Nestle [20:29]

The “Triple Duty Diet”

• Same eating pattern addresses hunger, obesity, and climate change: “Eat real food, processed as little as possible, with a big emphasis on plants.”

  “The diet that is best for preventing hunger, preventing obesity and its consequences, and preventing climate change is one in the same diet...” – Marion Nestle [21:44]

  “Michael Pollan... eat food, not too much, mostly plants. I took 700 pages to do the same thing.” – Marion Nestle [22:14]

[22:23] Food Supply, Waste, and Insecurity

• US food system overproduces; 4,000 calories per person/day—twice the need.

• 40% of food produced is lost, with 10% at the supermarket and 20% at home.

• Waste is “built in” via subsidy-based overproduction.

  “We produce 4,000 calories a day for every man, woman and little tiny baby... waste is built into the system? It's built, yeah.” – Marion Nestle [23:18]

[24:10] Can Anyone Do It Better?

• No country has fully realized a “triple duty” diet approach, but some European and Latin American countries offer lessons in policy and prevention.

[24:54] Systemic Change: “A revolution”

• Structural change requires shifting agricultural focus, public health political will, and corporate values.

  “We would need to change our electoral system so that we could elect officials who were interested in public health rather than corporate health.” – Marion Nestle [25:16]

  “If we don't do what we can to advocate for a better food system, we won't get it.” – Marion Nestle [25:57]

Segment 2: Mary Roach on Organ Replacements

[33:57] Introduction to Mary Roach

• Author of accessible, witty science bestsellers (Stiff, Bonk, Gulp, Packing for Mars).
• New book, Replaceable You: Explores breakthroughs in replacing body parts, from pig organ transplants to future 3D printing.

[35:04] Human Curiosity and Motivation

• Roach’s own aging sparked curiosity; chronicling stories of elective amputees, regenerative medicine, and surgeons’ perspectives.

  “I'm 66 and things are starting to go. So it's kind of ever present in my head.” – Mary Roach [35:07]

[36:19] How Amputation Has Evolved

• Pre-anesthesia: Speed was crucial—“get it off quickly.”

• Now: Surgical precision, nerve management to reduce phantom pain.

  “You can take nerves, the major nerves, and kind of wrap them around muscles so that they have something to do... so they're not, in the words of one surgeon, a downed power line sparking in the roadway.” – Mary Roach [36:49]

[37:18] Animal Parts for Humans – Why Pigs?

• Historical partnership: Hormel and Mayo Clinic worked to breed pigs with organs similar to humans.

• Pigs develop human-like heart disease, making them ideal study/test models.

  “The pig was described in one of their papers as a caricature of an obese human.” – Mary Roach [38:14]

[39:31] Tackling Organ Rejection

• “Hyperacute rejection” is immediate and severe with cross-species transplants.

• Solution: Genetic editing, e.g., removing the alpha-gal protein to make pig organs more compatible.

  “You don't want to put a pig organ into somebody without it having been genetically edited.” – Mary Roach [40:09]

[41:01] Religious Concerns – Is a Pig Organ Kosher?

• Roach interviewed surgeons and religious leaders.

  • Consensus: Organ transplants do not violate kosher or halal laws if purpose is life-saving and not consumption.

  “We're not eating them. We are saving lives. So it's okay to get a pig organ if you're keeping kosher.” – Mary Roach [41:25]

[41:46] The Future: Growing Human Organs in Pigs

• “Chimerism”: Growing a human organ inside a genetically-edited pig for transplantation.

• Ethical dilemmas loom (what if human cells affect animal’s brain?).

  “If they land in the brain, such that the brain starts to develop more like a human brain... do you need to treat the pig more like a human?” – Mary Roach [44:04]

[44:22] 3D Printing Body Parts

• At Carnegie Mellon, researchers print muscle with complex patterns mimicking real organs.
• Some success: Mouse with printed ventricle; printed heart valve.
  • “You're not just printing generic muscle. You have to print it in a very specific way to achieve the function that you want it to be doing.” – Mary Roach [45:15]

[46:25] Facing Our Own Biology

• Roach’s research makes her appreciate bodily processes.

• Recognizes not everyone likes explicit detail—especially her squeamish husband.

• Marvels at the mundane miracles of the body:

  “Sometimes I can't sort of share my appreciation for all these gooey bits and pieces of us that are performing miracles on a daily basis.” – Mary Roach [47:53]

[50:19] The "Beautiful-Ugly" of the Body

• French expression "belle laide"—internals like liver and heart are both magnificent and odd.

  “If you see a heart inside somebody's chest beating… it's kind of extraordinary. And it's doing that over and over and over for... like, if you're lucky, 80, 90, 100 years.” – Mary Roach [51:08]

Notable Quotes

• Marion Nestle: “The purpose of a supermarket is to sell as much food as possible to as many people as possible, as often as possible, at as high a price as they can get away with. I can't say that enough.” [16:46]
• Marion Nestle: “Froot Loops with vegetable dyes are still Froot Loops... nutritionally hilarious.” [08:12]
• Mary Roach: “If you see a heart inside somebody's chest beating... it's surprisingly active. That thing's like squirming around in there in this little space. It's kind of extraordinary.” [51:08]
• Mary Roach: “Sometimes I can't sort of share my appreciation for all these gooey bits and pieces of us that are performing miracles on a daily basis.” [47:53]

Timestamps for Key Segments

| Timestamp | Segment | |-----------|----------------------------------| | 00:57 | Introduction to Marion Nestle | | 04:24 | RFK Administration Discussion | | 06:17 | Food Policy Initiatives Dropped | | 10:35 | Public Health Silos | | 13:06 | Supermarkets & Slotting Fees | | 17:17 | Ultra-Processed Foods | | 20:29 | Environmental Impact | | 21:44 | Triple Duty Diet Concept | | 22:23 | Food Waste/Overproduction | | 24:54 | Food System Revolution | | 33:57 | Introduction to Mary Roach | | 36:19 | Evolving Amputation Techniques | | 37:18 | Why Use Pig Parts? | | 39:31 | Organ Rejection/Genetic Editing | | 41:01 | Kosher/Religious Aspects | | 41:46 | Chimerism – Human Organs in Pigs | | 44:22 | 3D Printing in Medicine | | 46:25 | Appreciating the Body | | 50:19 | "Beautiful-Ugly" Internals |

Episode Tone & Takeaways

• Language/Tone: Informed, wry, conversational—blending practical critique (Nestle) and vivid, humorous curiosity (Roach).
• Takeaways: The food and medical systems are complex, politically influenced, often illogical, and require critical public scrutiny and advocacy for meaningful reform. The science of bodies and biology is both wondrous and unsettling, but wholly fascinating.

Recommended for listeners interested in food systems, public health, medical science, and the quirky wonder of the human body.