This Book May Save Your Life

Everyday Health Hacks to Worry Less and Live Better

About the Book

#1 SUNDAY TIMES BESTSELLER • A hilarious, myth-busting survival guide that explains the weird and wonderful bodily functions that keep us alive—and how to make them work better for longer—from TikTok's favorite doctor, “the go-to expert for a generation” (The Telegraph)

“Dr. Karan Rajan reveals his health hacks that may save your life. . . . In a world of charlatans and social media snake-oil salesmen, he provides a voice of reason.”—Mail on Sunday
Your body is incredible, but it’s also out to destroy you. Your brain is like an early computer operating system, riddled with bad code, slow to load, and more likely to watch cat memes than go to sleep. You’d be a mess without your skeleton, but it can be a bony cage if you’re tortured by backaches, niggling neck pain, and knee joints that crumble under pressure. And your nose is a design disaster, getting blocked, springing leaks, and growing random tufts of hair.

You are the sum total of a lot of mistakes, trials, and errors, and you have to learn to live with them as best you can. That’s where this book comes in. Here’s everything you need to know to slow the inevitable decay that’s plagued your body from the moment of your birth.
You will:

• Enjoy the most epic and efficient dump of your existence
• Optimize brain efficiency by putting an end to multitasking
• Give your breath a sniff test to assess your health
• Start treating your eye socket dumplings with the respect they deserve

Here’s how to keep all your organs living in peaceful harmony so that you can enjoy a better, longer, healthier life.
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Praise for This Book May Save Your Life

“When you want to sort medical fact from medical fiction, Dr. Karan is your man. This is the only book that will have you laughing and learning in equal measure.”—Dr. Julie Smith
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This Book May Save Your Life

Chapter One

Exploring gut pipes and digestive processes

In my view of history, more lives have been saved by the hands of plumbers than doctors. Surgeons, physicians, and scientists get all the glory, but I feel it’s time a chunk of that credit should go to that humble guild responsible for modern sanitation and sewage infrastructure. Why? Because a country’s water system is directly linked to its population health. Without plumbers, deadly diseases like cholera would be rampant and there wouldn’t be much point in saving for a pension.

Plumbers and doctors might seem like very different professions. When it comes to upholding public health, however, they’re inextricably linked.

The body is a temple. That’s the phrase we often trot out when it comes to wellness, but it couldn’t be further from the truth. The fact is your body is a complex tower block with bespoke fittings, a series of overlapping drainage pipes, a sewage system with occasional backflows, many demanding tenants, and even a few secret passageways. Steady now . . .

If we were presented with the blueprint for its construction, most people would take one look at the seemingly impenetrable tangle of plumbing and look around for someone in the trade to make sense of it. Which is where medics like me come in. If we’re not on another job at the time.

Just as our ancestors eventually understood the benefits of civic sanitation, we can sometimes take a while to acknowledge the importance of keeping our human plumbing up to scratch. If your internal tubing sprouts a leak or a blockage point, it isn’t just a question of a call out and a hit to the credit card. The consequences can be life-threatening.

Over time, I’ve come to view my purpose as a doctor to be more than just a dispenser of pills and potions. In my surgeon’s gown and gloves, I might look like a civilized butcher, but there’s more to my role than that. Today, I think of myself as a mechanic for humans. A biomechanic if you will, and a tradesperson just like the plumber. In the same way that cars, buildings, and tools need regular maintenance, the human body requires self-care and regular upkeep to avoid—or at least delay—misery, mishap, and the morgue. With this in mind, let me take you on a tour of the concealed pipes, service passageways, and vents that form a central part of our anatomy, the gut.

Humble beginnings

Have you ever wondered how this all began? I don’t mean philosophically but simply which of your body parts was first out of the blocks from the moment of egg fertilization? Was it the brain? The heart? The backbone, or even the eyes? In answer, I would ask you to stop being such a poet about it, because the fact is that in that first magical moment you were nothing but an orifice indented on to a cluster of cells. That’s right. You started life as an asshole.

Nobody can escape this unfortunate fact. We all kicked off in the same way, and it isn’t pretty. The philosophers are allowed back in the room at this point, because of course this begs the question whether certain individuals every truly developed beyond this point.

Technically humans are deuterostomes. In other words, we belong to a group of animals whose blastopore (the first opening in the developing embryo) becomes its anus. Protostomes are animals whose blastopore becomes its mouth, but without exception we begin as bums, which is effectively the tail end of the gut. After the sperm breaks through the egg’s outer membrane, the embryo splits into many different cells, eventually becoming a blastula. The blastula cells tear open from the inside out, forming an outlet called the blastopore, which, as you may have guessed, will one day develop into a glorious butthole (arguably blastopore is a far more sophisticated name for your rusty sheriff’s badge, but for some reason it never caught on). Whatever you want to call it, the fact remains that your existence began as an embryonic, disconnected anus floating around in your mother’s uterus, which is both a harsh truth and a highbrow insult if you ever care to use it.

With the blastopore now winking and floating happily in that amniotic sac, it widens and tunnels into the other side of the blastula where a mouth is formed. Yes, this is sounding like one of those horror films you regret watching midway through, but bear with me. By week six, that ass-to-mouth alien hybrid has evolved into something altogether more human. By then, you have developed the beginnings of your intestinal tracts inside the umbilical cord, the safety rope connecting you to the placenta. Mercifully, perhaps, your eyes only start developing at week eight. Until then, you’re largely sheltered from the horrors of your own flesh twisting turning and mutating into an early version of what you are now. Traumatic stuff.

“You don’t want to do it like that”

If you’ve ever built anything from scratch, like a robot monster made out of cereal packets (just me?), the early stages of construction rarely see it take on a form that resembles the final product. This is perfectly epitomized by the shape of your nascent embryological gut when you’re a four-week-old human embryo. Through a series of elaborate origami-style folds, it transforms from a simple tube running up and down to an elaborate series of bulges and protrusions that include your liver, gallbladder, intestines, pancreas, esophagus, mouth, and stomach.

The one thing that always stumped me about embryology, and how our gut develops, is why it’s doing what it does. How does it know the purpose of its existence? Take for example the small intestine. It loops around itself in our embryological bodies and journeys both inside and outside of the body. The mid-gut, which eventually consists of your small intestine, along with about half of your large intestine and your appendix, grows at a rapid pace. Such is the speed of development that at first it exceeds the capabilities of your primitive abdomen to contain it. Instead, these loops of intestine are exiled for a few weeks before snaking their way back in once your belly can contain them.

If any errors occur during this delicate dance, some babies can be born with an omphalocele, in which the intestines have developed in a sac outside the abdomen. This is frightening to see, even for a surgeon, who must attempt to rehouse it back where it belongs with immediate surgery. Then there are anorectal malformations that result in an underdeveloped anus and rectum that prevents normal stool passage; malrotation, when the intestines don’t fold properly and are prone to twisting; and intussusception, in which the intestine retracts in on itself like a telescope causing bowel blockage. These are just scratching the surface of what can go wrong if just one element of the complex developmental choreography of the gut goes awry. It can result in lifelong health complications, and sometimes even death.

With all these various tubes, twists, and turns you can see why I often talk about the gut in terms of plumbing. Known as the gastrointestinal system (or GI for short), it’s one long and twisting pipe with valves, fittings, and fixtures. It even boasts the functionality of a range of domestic appliances. What’s more, the entire system is governed by what we now call a smart device.

Snack activation

When it comes to eating, guzzling down your meal deal is not as simple as draining bathwater into a down pipe. Yes, your lunch drops into a vertical tube once swallowed, but it’s here that digestion takes place so your body can acquire energy from food, which makes it so much more complex than simply letting gravity take over. The path from mouth to anus is fraught with danger at every turn but also quite magical in the process, thanks to some botching over the course of evolution that has resulted in a system that works.

The opening gambit of digestion is not marked by the moment that food hits your tongue. Those gears started turning long before you sat down to eat. Even when you poured the boiling water into your pot of instant noodles, releasing those sweet and sour aromas to seduce your nostrils, your digestive system was already activated. That trigger fired when the thought of a snack proved irresistible. As a result, a cascade of reflexes kicked off to stimulate the secretion of salivary juices, along with the production of more stomach acid and various enzymes in preparation for the feast.

The consumption of food, and the subsequent harvesting of fuel from it before the disposal of what’s left over, is an act that is core to your well-being, which is why the gut was one of the first structures to develop when you were in the womb. From that blind, floating asshole in the moist environment of your mother’s uterus, a miracle took place.

Yes, you developed into a fetus, but more immediately you became a leech.

The umbilical cord is the safety rope that tethered you to your mother. It’s the external plumbing system that doubled not only as your lifeline and source of food but a parasitical portal to the poor woman whose existence was set to revolve around you for quite some time to come. You enjoyed an idyllic existence in your amniotic sac, surrounded by fluid containing your own urine, free from the worries of metabolism and waste management. All your nutrients were conveniently provided to your door, nature’s ultimate delivery service. The only cost was the discomfort you caused your provider for nine long months—until the terms of service changed.

About the Author

Dr. Karan Rajan
Dr. Karan Rajan is an NHS surgeon and one of the biggest health and science creators on social media. Since 2020 he has amassed more than seven million followers across his channels with his refreshingly frank medical myth-busting and health-advice videos which combine education, entertainment, and generous servings of dark humor. In addition to being a regular advocate of health promotion on behalf of the NHS and the UK government, he has also worked closely with the UN, the World Health Organization, and the British Red Cross in an ambassadorial capacity. He is a senior clinical lecturer at the University of Sunderland School of Medicine and was formerly at Imperial College London. More by Dr. Karan Rajan
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Random House Publishing Group