BY DR. GURPREET SINGH PADDA, MD, MBA, MHP, AND AMI MICHELLE GRIMES
Your head is not in charge.
Your gut is.
The anatomy chart says the brain commands and the gut obeys. The chart is upside down.
The first brain, and the one that answers to it.
Evolution built the gut first. Before chordates existed, primordial organisms were essentially digestive tracts that consumed and grew, and the human gut is the outer surface of the animal folded inward into a tube — the villi that line it dwarf the skin on the outside. The organ in your skull arrived millions of years later, tethered to the first by the vagus nerve.
That order still holds. The gut runs its own nervous system with roughly as many neurons as your spinal cord — 168 million of them — and it manufactures the overwhelming share of the body’s serotonin. The part of the vagus that serves it is built almost entirely of the thin, slow fibers that carry reports, so the traffic runs mostly upward. The second brain is downstream, and it is reading what the first one sends.
Treat the first brain before you try to fix the second.
This book is about what an inflamed, leaking, badly fed gut does to the brain that thinks and to the nervous system that hurts — what causes it, how it is measured, and what the evidence actually says about correcting it.
Thirty-three chapters. Every claim referenced.
Chapter 0 sets the evolutionary premise. The thirty-two that follow work through the wall, the wire, the flora, the bile, the drugs and the food supply.
0 · The Primordial First Brain Stomach of a Hyena
1 · The First Brain on Fire Anxiety is gut fire
2 · The Pharmaceutical Acid Wash Nobody works in the bag
3 · The Vagal Highway Two doctors, one nerve
4 · The Permeable Fortress The test you paid for cannot see the wall
5 · The Fatty Liver Furnace Alcohol you never drank
6 · The Intrinsic Factor Failure Normal Is Not Fine
7 · The Collagen Collapse Collagen is the wall
8 · The Lipid Fire What You Fried Last Week
9 · The Nitric Oxide Crisis Your gut is suffocating
10 · The Sunshine Hormone It’s a hormone
11 · The Disc Microbiome Bacteria in your spine
12 · The Second Brain Microbiome Waistline predicts leaking brain
13 · The Trauma Blueprint Fear paralyzes the gut
14 · The Starved Enterocyte Full, but starving inside
15 · The Artificial Food Supply Your microbes read labels
16 · The Immune Matrix Immune system isn’t confused
17 · The Sleep Deprived Microbiome Your gut has jet lag
18 · The False Parasite The wrong enemy
19 · The Metabolic Fast Six Meals a Day?
20 · The Hypochlorhydria Myth The pill you can’t quit
21 · The Narcotic Bowel Side Effect or Disease?
22 · The Glyphosate Harvest The Antibiotic on Your Salad
23 · The Bile Acid Disconnect Bile Is a Hormone
24 · The Cravings of the Dysbiotic Mind Cravings Have a Schedule
25 · The Diagnostic Breath and Biomarker Your gut exhales its secrets
26 · The Biotoxin Blueprint Fix the Basement First
27 · The Eradication and Repopulation Paradox Weeds Were Never the Problem
28 · The Biliary Flush Where does bile go?
29 · Rebuilding the Mucosal Fortress Measure the wall
30 · The Integrated Terrain No Discharge Date
31 · The Histamine Storm Not Allergic. Fermenting It.
32 · The Nicotine Paradox It was never the molecule, it’s where you put it
It tells you where the evidence is weak.
There is a great deal of confident nonsense written about the gut. Most of it works by showing you the studies that agree and quietly skipping the ones that don’t.
This book does the opposite, on purpose.
Chapter 1 opens by dismantling a claim I taught for years, and one this book would be easier to sell with: that gut-made serotonin runs your mood. The gut does make the overwhelming share of the body’s serotonin — and serotonin cannot cross the blood-brain barrier, so there is no tanker of calm running from the colon to the cortex. Chapter 0 does the same to the tidy vagal ratio everyone quotes: nobody has counted those fibers in a human vagus. Both corrections weaken a case I am making. Both are in the book.
Every chapter carries a Deep Dive: the chapter, continued, with more of the evidence, the strongest case against it, and what would change my mind. Where the evidence is mixed, both sides are on the page. Where a trial argues against the position in the chapter, that trial is printed too.
A book that only gives you the good news isn’t a book you can trust with your gut.
The Deep Dives go further than the chapters have room to, and they are the reason this series takes as long as it does.
Get your copy.
Kindle and paperback, on Amazon.
Thirty-three chapters, every claim referenced. Each chapter ends with a code that opens its Deep Dive, where the chapter keeps going.
Prefer to watch?
Every one of the thirty-three chapters has a video of its own, with that chapter’s own slides. Chapter 0 sets up the whole argument — start there.
Chapter 0 — The Primordial First Brain. Why the gut is the first brain, and the one in your skull the second.
Who wrote this
Dr. Gurpreet Singh Padda, MD, MBA, MHP is an interventional pain physician in St. Louis. His clinical work runs on one principle: treat the terrain, not the symptom.
Most chronic disease he sees — cognitive decline, chronic pain and the gut failures in this book among them — is downstream of metabolic, structural and inflammatory problems that are measurable and modifiable, and the symptom that brings someone through the door is rarely the thing that needs correcting. He tests what others assume, says plainly where the evidence is strong and where it isn’t, and builds one correction across the whole terrain rather than treating four problems separately.
The Angry Gut is written with Ami Michelle Grimes. He practices in St. Louis, Missouri.
If you’re in the St. Louis area
The book will tell you what to measure and why it matters. It can’t tell you what your terrain is doing.
Dr. Padda sees patients in person in St. Louis. A terrain evaluation looks at what this book looks at — what the intestinal wall is built from, what the flora are being fed, what years of acid suppression and antibiotics have done to the chemistry, and the inflammatory load most panels never test for — and builds one plan across all of it.
This is an in-person evaluation in the St. Louis metro area. If you’re elsewhere, take the book to your own physician — the book is written to support exactly that conversation.
In-person consultations · St. Louis, Missouri
Your gut has been rebuilding its own lining every few days since the day you were born.
It will keep doing it, for as long as you stop setting it on fire.
The Brain
One terrain, the same standard of evidence. Each book stands alone; read together they are a single case.
The Starved Brain
The brain, and what it is built from. Ten chapters on what decades of quiet malnutrition do to an organ, in a population that has never missed a meal — and why so much of what gets called normal aging is a supply problem.
Published. Kindle and paperback. · thestarvedbrain.com
The Pained Brain
The nervous system, and why the pain outlasts the repair. Twenty-two chapters on why a worn joint and a convincing scan explain so little, and why chronic pain is so often a systemic metabolic failure that has chosen a joint to announce itself in. 2,291 references documented across its Deep Dives.
Published. Kindle and paperback. The Deep Dives are available now, one chapter at a time. · thepainedbrain.com
The Angry Gut — you are here
The gut, which supplies and inflames both of the above. Thirty-three chapters on the organ upstream of the other two books: what an inflamed, leaking, badly fed gut does to the brain that thinks and to the nervous system that hurts.
Published. Kindle and paperback. · theangrygut.com
The Dopamine Brain
The reward system, and what it learned to want. Why we do what we do, when we do it: learned behavior, motivation, and what finally gets us to move.
Published. Kindle and paperback. · thedopaminebrain.com
The Humbled Brain
In progress. On limitation, and the admission that we are not in charge.
Book five, and the last in the series. Being written now. · thehumbledbrain.com
The terrain is one system, and it is the reason these are five books rather than five subjects. A brain starved of the materials it is built from, a nervous system left in a fire that never finished, a gut that feeds and inflames them both, a reward system that learned what to want and when to move, and a mind that has to admit it is not in charge are not five problems. They are one failure, read from five sides — which is how the body has it, even though one side at a time is how the reading has to work.
THE ANGRY GUT
The First Brain: Older Than Thought, and Still in Charge
© Dr. Gurpreet Singh Padda, MD, MBA, MHP, and Ami Michelle Grimes
Work with Dr. Padda → regen.md
This book and website are educational. They do not constitute medical advice, do not create a physician-patient relationship, and are not a substitute for evaluation by a qualified clinician. Do not start, stop, or change any medication on the basis of this material — including acid suppression, which several chapters discuss and which is not safe to stop abruptly without supervision. Significant dietary change requires medical supervision if you take medication for diabetes or blood pressure, are pregnant or breastfeeding, or have kidney, liver, gallbladder, or pancreatic disease or a history of disordered eating. Individual results vary.