Radiolab – “Guts” (April 2, 2012)
Hosts: Jad Abumrad, Robert Krulwich
Notable Guests: Mary Roach, Fred Kaufman, Arlene Shaner, John Reiner, Professor John Cryan, Carl Zimmer, Joan Oleira

Episode Overview

In this compelling episode of Radiolab, the team embarks on a deep dive—sometimes literally—into the mysterious world of the human gut. Exploring everything from scientific history and strange medical case studies to the intimate connections between our digestive system, brain, and emotions, “Guts” combines hands-on reporting, quirky humor, and scientific curiosity. The episode weaves together the bizarre tale of fistulated cows, the groundbreaking studies of digestion in the 1800s, the emerging science of microbiota-gut-brain interactions, and a powerful personal story of illness and resilience.

Key Discussion Points & Insights

1. The “Yuck Factor” & Fistulated Cows

[01:04–03:13]
Guest Mary Roach, author of “Gulp,” shares her up-close encounter with a fistulated cow—an animal with a surgically created “window” into its stomach, used for research.

• Mary Roach’s enthusiasm: “I’m the kind of person where… they’ll be like, 'Ms. Roach, you need to step back. Your head is actually inside the body cavity.'” (01:33, Mary Roach)
• Describes the experience of literally plunging her arm into a live cow’s stomach: “Keep going, keep going, and I’m literally up to my shoulder inside this cow.” (02:48, Mary Roach)
• The sensory experience: it's warm, steamy, and the stomach muscles squeeze back: “It’s groping you back.” (03:55, Mary Roach)

2. Transformation Within: How The Gut Mediates “Outside” and “Inside”

[04:40–05:35]

• Fred Kaufman muses on the gut as a site of “magical transformation:” “You take something outside of your body, you put it in your body, and it turns into you.” (04:48, Fred Kaufman)
• The "donut" analogy: “The human body is a torus. We’ve got a hole going through the middle of us... what seems to be inside our stomach actually is always outside us.” (05:00, Fred Kaufman)
• Jad and Robert set up the episode’s thesis: “We’re going to take this thing that’s deep inside us and turn it inside out.” (05:27, Robert Krulwich)

3. A Window Opens: The Story of Dr. Beaumont and Alexis St. Martin

[06:05–16:04]

• Historical case: In 1822, fur trapper Alexis St. Martin is accidentally shot, leaving a permanent hole (fistula) in his stomach—offering Dr. William Beaumont unprecedented access to a living digestive tract.
• Beaumont’s “stomach fishing” experiments: inserting different foods tied to a string into the stomach, pulling them out to inspect digestion progress.
  • “He attaches them to a silk string and... inserts them through the artificial opening into the stomach.” (11:04, Arlene Shaner)
• Discoveries:
  • Digestion is chemical, not mystical: “Beaumont, one of his big discoveries was…actually, there are no secret forces… it’s a chemical.” (14:25, Fred Kaufman)
  • Identification of gastric juice (enzymes) and its digesting power, both inside and outside the body.
• The ethical ambiguities: The personal dynamics between Beaumont and St. Martin—“Maybe he even thinks, this man could be my ticket out…” (09:47, Fred Kaufman)
• St. Martin’s status as a medical subject, his struggles, and post-mortem legacy: “His family let his body rot in the sun for three days, then buried him… put big rocks over him so he would not be exhumed.” (16:04, Fred Kaufman)
• Memorable quote: “How does food become us?” (08:38, Jad Abumrad)

4. The Gut’s Inner Rainforest: Microbiome & Identity

[17:32–20:54]

• Guided by Carl Zimmer and John Cryan, the team explores the vast microbial ecosystem in our intestines.
  • Robert: “It’s like a rainforest.” (19:34)
  • Tim Howard: “About 100 trillion microorganisms... if you made them into one lump... about 3 pounds—like your brain.” (20:48–21:13)
• Every person acquires their first microbes during birth and then through life’s contact with people, animals, and the environment.
• The gut as a “collective” that’s not just you: “The part of you that turns the world outside into you isn’t just you.” (18:43, Robert Krulwich)

5. Mind–Gut Connection: How Microbes Affect Mood (Mouse Study)

[21:13–29:01]

• Professor John Cryan investigates whether certain bacteria (Lactobacillus rhamnosus) affect the behavior and neurochemistry of mice.
  • Experiment: Mice fed the bacteria displayed less "behavioral despair" in a water test—they didn’t give up as quickly as control mice.
  • “The mice that eat the bacteria, they hit the water, the stress hormones come online. But... in comes GABA.” (27:19, Robert Krulwich)
• Discovery: Those bacteria affected levels of GABA (a calming neurotransmitter) and stress hormones in the brain, via the vagus nerve.
  • “If you cut the nerve, the mice went back to being quitters.” (29:01, Robert Krulwich)
• Memorable quote: “They behave like as if they were on Valium.” (27:29, Professor John Cryan)

6. Human Evidence: Probiotics, Mood & the Source of Happiness

[29:16–32:43]

• Discussion of a French clinical trial where people taking probiotics showed lower anxiety and stress.
  • “People who took those probiotics said they felt less angry, less anxious, and less depressed.” (30:33, Robert Krulwich)
• Surprising stats: “80% of all the serotonin in your body is in your gut.” (31:04, Joan Oleira)
• Implication: Our gut bugs have us on a chain—our moods and psychological well-being may be shaped, in part, by our microbes.
  • “Let’s think about how we can treat people’s psychological disorders with bacteria this way.” (32:01, Tim Howard)
• Poetic reflection: “A lot of our moods come from the same organ that produces… It does make a little bit more sense from the perspective of evolution.” (32:32–33:18, Joan Oleira)

7. The Personal Story: John Reiner and Life Without Eating

[35:11–54:36]

• John Reiner’s experience of Crohn’s disease, emergency surgery, and the subsequent need to live without using his gut (on intravenous feeding for months).

• Emotional and existential hunger:

  • Vivid daydreams/memories of food (40:59)
  • Attempting to relive sensations by touching and smelling food—“I plunge my hands into the chocolate cake… to get some sensation of connection with food.” (44:29, John Reiner)
  • Humiliation and feeling of failure as a parent and provider due to inability to eat (42:46, John Reiner)

• The deep psychological impact:

  • Depression, strains in marriage, escapist behaviors—“It was just very hard to face.” (46:27, Jenny Steiner)
  • Moment of despair: “You’ve reached the end of the line… were you really having suicidal thoughts?” “I don’t know that I would have thrown myself in, but it was the first time I was standing at the edge thinking about it.” (48:54–48:57, Jad Abumrad / John Reiner)
  • Peculiar “turning point”—trying to find hope by visiting a favorite restaurant, Chanterelle, only to discover it closed (48:35)
  • Surreal moment: John helps cook a stranger’s pork chops in their backyard (50:03)

• Culmination:

  • Forced by medical circumstance to try eating regular food again. Taste buds gradually regenerate, culminating in a joyous moment: “I could feel that… fried egg congealing with the crunchy bacon and the crunchy toast… I can see that I’ve got little bristles, I’ve got little bumps on my tongue. And I can taste this fantastic $3 sandwich.” (53:07–54:10, John Reiner)

• Memorable quote: “Everybody eats when they come to my house.” (55:00, Jad Abumrad, referencing food and belonging)

Memorable Quotes

• “We are these sacks of guts. And we walk in these skeletons... and we never even see them.” — Mary Roach (05:44)
• “How does food become us?” — Jad Abumrad (08:38)
• “Nobody understood it because you can’t see.” — Fred Kaufman (08:48)
• “It’s a whole universe down there.” — Robert Krulwich (19:17)
• “You have an oil well of happiness in your gut, and if you get the right pump, you could feel happy more of the time.” — Robert Krulwich (31:13)
• “It was like, pow… I am Jewish. These are my people.” — John Reiner (40:11)
• “Please give me some time alone with my bundt cake.” — John Reiner (45:16)
• “I have food, if not in me, at least on me.” — John Reiner (44:39)
• “I can taste this fantastic $3 sandwich.” — John Reiner (54:10)
• “Everybody eats when they come to my house.” — Jad Abumrad (55:00, quoting a classic food song)

Notable Moments & Timestamps

| Time | Moment/Segment | |---------|--------------------------------------------------------------------------------------------| | 01:33 | Mary Roach’s “head inside the body cavity” remark—diving deep into reporting | | 02:48 | Up to her shoulder inside a cow’s stomach | | 03:55 | “It’s groping you back”—the stomach is muscular, active | | 09:47 | Ethical ambiguity: St. Martin’s role as research subject and “ticket out” for Beaumont | | 14:04 | Proof that digestion is chemical, not mystical | | 21:13 | The gut as a microbial organ as significant as the brain—you’re home to a “collective” | | 27:29 | “They behave like as if they were on Valium” (chilled out mice, thanks to gut bacteria) | | 31:04 | “80% of all the serotonin in your body is in your gut” | | 44:29 | “I plunge my hands into the chocolate cake…”—powerful visual of food hunger | | 48:35 | “Chanterelle has closed.” John’s search for hope meets disappointment | | 54:10 | Recovery and joy: “I can taste this fantastic $3 sandwich.” | | 55:00 | Musical outro—celebrating food and shared experience |

Themes & Takeaways

• The gut is not just a digestive organ, but a site of profound scientific, historical, and emotional significance.
• Scientific understanding of digestion evolved from mystical “vital forces” to chemistry, thanks to curious (and sometimes ethically murky) experiments.
• Our mental health and identity may be astonishingly intertwined with our gut’s microbial denizens.
• Personal stories reveal the existential and psychological depths of our relationship with food and the act of eating.
• Sometimes, even a simple meal after adversity becomes a celebration of life and connection.

For anyone who hasn’t listened, “Guts” is a surprising and moving tour through science, history, and human vulnerability—a testament to the wonder of what lies (literally) within.