Introduction

1 If you look closely, it's all done by the nose.
2 Master, I will taste rotten meat.
Pride and Prejudice Surrounding the 3rd Liver
4. If you chew thoroughly and eat slowly, you can even pay off the national debt.
5th place, stomach acid and the love and hate of two men
6 Dirty spit, scary spit, good spit
I'm happy because I can eat with my mouth.
8 How to Survive Being Eaten by a Whale
9 The Counterattack of the Feed
10 People Who Died From Eating Too Much
11 The smuggler's most reliable companion, the digestive tract
12 Warning! May explode
13 People die and leave behind intestinal gas.
14. Is foul-smelling intestinal gas really that bad?
15 Can't you go in through the exit door?
16 Elvis Presley, died of constipation!?
17 I'll fix it perfectly, if you just endure the disgusting things

Acknowledgements
References
Translator's Note
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From nose to intestinal gas, "Made in the body's factory"
The great human affairs of ingestion, decomposition, absorption, and excretion

If you think about it, it's all done by the nose!?｜Pride and prejudice surrounding the internal organs｜Dirty spit, scary spit, good spit｜Can't I go in through the exit door?｜My mouth has an automatic brake｜I'll lend you my toilet.

It unravels the process of food passing through the mouth and into the esophagus as a journey, and introduces various human chemical phenomena, nutrient distribution, scientific experiments, and statistics that occur at each stage in an interesting way.
Interesting topics such as the hidden workings of the nose and the relativity of taste, the story of the liver and intestines, which are so-called disgusting foods, the health benefits of prolonged chewing, the history of stomach anatomy and the mystery of gastric acid function, the medicinal effects of saliva, the function of mastication (chewing) of the mouth and the physics of food, the truth about intestinal gas, the misconceptions about constipation, stool as a barometer of health, the interrelationship between bacteria and the large intestine, and the miracle of small intestinal villi are constantly pouring out.
Roach deftly treads the line between irreverence and suspense, creating tension while simultaneously evoking awe at the dignity and sophistication of the human body.

How can a wine taster tell the difference between a $10 bottle and a $100 bottle? Can chewing your food thoroughly help pay off the national debt? Saliva is teeming with bacteria, so why do animals lick their wounds? Why don't suicide bombers hide their bombs in their anuses? Why is the stomach intact, even though it breaks down food? Why do crunchy foods taste so delicious? Can people die from constipation? Did Elvis Presley really die from it? How much can we eat before our stomachs burst? Why aren't human stomachs as big as cows'? Why do dogs eat their own feces?

To provide clear answers to these questions, the author visits the laboratories of a pet food manufacturer, a Dutch saliva lab, and an Arctic Eskimo village where they enjoy eating intestines and liver. He also explains the somewhat shocking-sounding fecal (colon bacteria) transplant surgery—changing the gut flora is far more effective than changing the diet to prevent and cure disease—and even uses an endoscope to capture the fate of food in the stomach, vividly describing the process.
Sometimes, through outlandish topics like enema nutrition and autophagy, it subtly reveals scientific truths that we may not otherwise be aware of, such as the nutrient absorption rate of the colon and rectum or the nutritional value of stool.
We pursue the hard-chewing truth of the so-called 'Fletcher Theory', acknowledged by Henry James and Franz Kafka.
As you travel the world with Roach, you'll meet murderers, mad scientists, Eskimos, and rabbis.
You might be startled to see an exorcist performing a ritual on a person's stomach, or perhaps you might be relieved to learn that terrorists, for practical reasons, cannot hide a bomb in the digestive tract.

Let's just taste a few of the interesting or impressive facts revealed in this book.
Is it wrong to eat intestines, liver, tendons, blood, and insects? Unsightly intestines and liver are said to be high in protein and a nutritious food source and an excellent substitute for vegetables.
This may be proof that Korean food culture is valid or excellent.
If you chew and swallow roughly, will it really be indigestible? If you chew and swallow roughly, any food will be processed by the small intestine.
It is said that the human digestive tract is designed to squeeze as much out of food as possible, so there is no need to be picky.
Could the human mouth possess a braking system far more rapid and sophisticated than the brakes found in a Lexus? More astonishing than the well-known strength of our jaw muscles is our sophisticated defensive instinct.
It's amazing how it works before we even realize we need to be careful.


“People are surrounded by little accessories.
“You’ll be amazed to learn that it’s a huge pipe.”
“I just can't understand.
“How can an idol singer be more precious than my body?”

“The greatest irony is that all life began in the digestive tract.
They say that the brain grew out of necessity to find food, and hands and feet grew out of necessity to pick up food.
As the body grew larger, a circulatory system was needed to supply energy fuel to every corner of the limbs, and in this way, the human body structure became more and more complex.
The part that reveals that “traces of this evolution still remain in the human digestive system” is impressive.

“Gorillas spend all day digesting leaves.
You sit down, chew it, and then it cooks in your stomach.
So how can you afford to use your brain for higher-level thinking?” “What you eat is important.
But a person's humanity is determined by how they eat it.
We should be grateful for all the miracles that make us human, including digestive juices, enzymes, intestinal villi, the discovery of fire, and the development of cooking techniques. … Take gorillas, our close relatives. Although gorillas are primates like us, they have been relegated to the second place in the hierarchy because their digestive tracts are less developed and therefore less efficient at producing calories.
Gorillas eat a huge amount of uncooked grass every day, just like cows.
I can relate to the part where he says, “This is how we live each day with the energy that is created through fermentation in our bodies.”


“We humans are blinded by ignorance, pride, and immediate gain.
So, I rashly believed as true the baseless speculations I had come up with myself or heard from someone else.
All while completely ignoring the truth that the body shows.
However, the signals the body sends are the crystallization of wisdom acquired by all life on Earth over millions of years of evolution.
“The human mind detests excrement as dirty, but the human body has no understanding of why excrement is dirty.”