The microbiome, a cutting-edge research field in modern medicine, is receiving significant attention in health and aging.
There are more microorganisms living in our bodies than there are cells in our bodies.
What is needed for healthy aging is to form a healthy symbiotic network with microbes.
This book is a detailed guide to aging healthily with microbes, and an innovative guide to the future world of microbes that will lead to longevity.

There are far more microorganisms than the tens of trillions of cells that make up our bodies, and most of them, except for a few that cause disease, form a symbiotic relationship with the cells in our bodies.
We depend on each other, help each other, and co-evolve together.
In particular, it is becoming increasingly clear that the help of microorganisms is essential for healthy aging.
This is the subject of this book and it is a matter of concern to us all.
The fountain of youth, necessary for healthy aging, is not in some distant utopia, but right within our own bodies, and that fountain is teeming with microorganisms.

---From the translator's note

In conclusion, this book approaches aging as a lifelong process.
It's not that we wake up one morning and suddenly find ourselves old. Our health is built up over our lifetime through our individual strengths and vulnerabilities.
Therefore, I sincerely hope that this book, written with the intention of guiding the aging process in a more positive direction, will provide readers with new ways to support and support the microbes that exist in our bodies and all around us, so that we can live as vibrant and healthy lives as possible.
“There’s nothing you can do about age.
But growing old is a choice.” ---From the “Preface”

One of the most exciting and cutting-edge areas of research in aging science involves the oldest organisms on Earth.
It is ‘microorganism’.
Unlike the high-tech products we use to try to turn back the clock on aging, bacteria have been around for over 3.5 billion years, dating back to when the Earth was covered in boiling water.
While Earth's climate has changed dramatically over the past billions of years, microbes remain a persistent presence everywhere: in the air we breathe (they created the oxygen in our atmosphere in the first place!), on the chair you're sitting on, and in the food in your refrigerator.
In fact, can you believe that there are more microbes on the palm of your hand than on the entire human population on Earth?
---「01.
The fountain of youth...
"It's full of microbes?"

It is known that human lifespan is determined by 25% genetics and the remaining 75% by environmental factors.
What this means is that we can control the majority of factors that affect our health and longevity.
Therefore, it is not true that children are destined to develop cancer just because their parents have cancer.
While we may inherit genes that predispose us to cancer, our future will be determined far more by the environmental conditions in which we live.
It is now clear that the most representative of these environmental conditions refers to the microorganisms that are most closely related to us.
---「01.
The fountain of youth...
"It's full of microbes?"

It's not easy for us to judge a person's age by their face, but using microbes, it becomes possible.
Because microbes are integral to the aging process and constantly adapt to the changing internal and external environments of the body, simply scraping the microbes from the forehead with a cotton swab and examining their composition can estimate age within an error of less than 10 years.
Especially after the age of 50, the microbial composition shows a clear difference compared to younger people.
Research into the processes and causes of changes in the composition and diversity of these microorganisms as we age is only recently beginning.
---「02.
Your Microbiome is Glowing: From "Skin Microbiome"

In the near future, it's not hard to imagine storing your own skin microbiome for 30 years, or even creating a skin rejuvenation cocktail made with vibrant microbes harvested from young people.
Furthermore, if we find microorganisms related to hair growth, we can use them to treat baldness by increasing the health of hair cells.
And if we could use microbes to improve the health and longevity of hair cells that produce pigment, we could potentially prevent graying as we age.
---「02.
Your Microbiome is Glowing: From "Skin Microbiome"

What role do microbes play in Alzheimer's and other types of dementia? While research is still in its early stages, numerous reports suggest that the microbiome directly or indirectly influences these diseases.
The fact that the incidence of Alzheimer's disease is much higher in developed countries suggests that factors such as high sanitation, Western-style eating habits, and resulting negative changes in microorganisms may be involved.
The link between Alzheimer's disease and microbes is also supported by the fact that urban areas have a 10-fold higher incidence rate than rural areas, which are rich in microbes.

---「03.
From "Follow the Microbes: Microbes and the Brain"

A representative example is a large-scale retrospective study conducted in the UK on antibiotic use among 200,000 depressed patients.
A one-year follow-up study of patients who had been administered one type of antibiotic more than once found that seven types of antibiotics increased depression, and among them, depression increased by 50% in the group that had been administered penicillin more than five times.
Other antibiotics also increased anxiety.
......
Therefore, the overuse of antibiotics has been expanded to affect not only physical health but also mental health such as depression, anxiety, and stress.
---「03.
From "Follow the Microbes: Microbes and the Brain"

There are surprising research findings linking oral hygiene, the oral microbiome, and dementia.
A large study of twins found that twins who lost their teeth before age 35 had a higher incidence of dementia.
The most surprising statistic is that the group that did not brush their teeth had a 22-65% higher risk of dementia than the group that brushed their teeth three times a day.
---「04.
Healthy Smile, Healthy You: From Oral Microbiome

Should I get a flu shot? Yes! The flu is a viral infection caused by the influenza virus, primarily affecting the nose, throat, bronchial tubes, and sometimes the lungs.
Most of us have suffered from the flu to some degree at some point.
These include fever, muscle pain, headache, sore throat, cough, chills, and fatigue.
Older people are particularly susceptible to the flu.
80-90% of deaths from influenza are in people over 65 years of age.
This is because as we age, our immune systems weaken and we become more susceptible to infections, which increases the incidence of influenza and can worsen underlying medical conditions such as heart disease, lung disease, and asthma.
---「05.
Let's take a deep breath: from "Lung Microbes"

“Humans and Helicobacter pylori clearly have a history of co-evolution.
This coevolution will take its toll as humans age, sometimes in the form of stomach cancer, and sometimes in the form of less serious conditions like stomach ulcers.
However, the benefits of H. pylori infection in childhood are not yet clearly understood, but it may have the advantage of fighting off infections by other bacteria.
Because we already know that a healthy microbiome is important, and Helicobacter pylori certainly falls into this category.
Humans have lived alongside this fungus for at least the past 100,000 years, so it must have played an important role.
But now, in the United States, Germany, and Scandinavian countries, less than 5% of children carry the bacteria.
This phenomenon is a frightening ecological shift that has occurred over a period of just a few generations.
“We need to make good use of our heritage, but it seems we are not doing so.”
---「06.
From "The King of the Stomach: Stomach Microorganisms"

If you change your diet to a high-fiber, low-fat diet, your microbiome will change within three days.
Changes in diet can alter more than half of the human microbiome, or 57%.
In comparison, genetic mutations only alter about 12% of the microbial community.
---「07.
From "The Holy Land of Microorganisms: Gut Microbes"

Our bodies have evolved in a symbiotic relationship with the microorganisms within us.
Therefore, it is essential for health and longevity to avoid disturbing the intestinal microbiota ecosystem as much as possible.
Disruption of the gut microbiome has devastating consequences, increasing the risk of chronic gastrointestinal diseases such as ulcerative colitis and irritable bowel syndrome, as well as metabolic diseases such as type 2 diabetes and obesity.
Therefore, much research is being conducted to identify specific “core” gut microbiomes that may be responsible for these specific diseases.
The environmental factor that can have the greatest influence on the composition of the gut microbiome and that can be controlled is diet.

---「07.
From "The Holy Land of Microorganisms: Gut Microbes"

Further evidence that gut microbes are involved in cardiovascular disease comes from fecal transplantation experiments. When feces from mice with high TMAO levels are transplanted into mice with low TMAO levels, both TMAO levels and the abundance of microbes with TMA synthase increase.
It's astonishing that simply transplanting feces (and the microbes within it) can alter the risk of cardiovascular disease! While this finding would have been unimaginable just a decade ago, research is now progressing at a rapid pace to elucidate how microbes contribute to heart attacks and strokes.
Perhaps in the future this treatment will be equally successful for humans.
---「08.
From “Microbes that Lead to Love: The Heart and Microbes”

Vaginal health is closely related to the microorganisms that reside in the vagina.
If strategies are developed to modulate or supplement specific vaginal microbes, treatment of vaginal infections could be improved and vaginal health during menopause could be significantly improved.
Because the gut microbiome may regulate estrogen levels after menopause, it is hoped that dietary changes including specific probiotics, prebiotics, and fermented foods may one day improve menopausal symptoms.
Because the vagina is composed of a mucosal surface that is closely linked to the immune system, attempts are being made to use vaginal microbes as vaccines or to alter immune responses.
---「09.
From “Women are not miniature men: Menopause and the vaginal microbiome”

One of the most groundbreaking findings across all fields of cancer research is the potential for the microbiome to be harnessed to enhance the efficacy of immunotherapy.
To explain this fact, we need to look at the basic principles of immunochemotherapy.
Immunotherapy uses immune checkpoint inhibitors to block immune checkpoints that interfere with the immune response.
These anticancer drugs trigger an immune response, enabling our body's own defense system to fight the cancer.
In other words, immunotherapy increases or restores the function of the immune system to stop or reduce the proliferation of cancer cells and also blocks the metastasis of cancer cells.
… … Two papers published in 2015 turned the entire field of immunotherapy upside down by announcing that microbes could modulate the effectiveness of cancer treatment, and served as an opportunity to bring the role of microbes to the forefront in traditional cancer treatment.
---「10.
From "Meeting Cancer: Microbes That Help Treat Cancer"

Another question arises here.
If inflammatory aging is so detrimental to our bodies and longevity, why hasn't it been eliminated through evolution? The simple answer is that inflammatory aging primarily occurs in older individuals, well past the reproductive stage, so there's no evolutionary pressure to eliminate it.
Evolution is so closely linked to reproduction that it seems genetically unrelated to how long we live after producing offspring.
Inflammation is also essential for survival and protection against infections and other diseases in early life, especially during the reproductive years.
Survival itself at this time is also key to longevity.
Therefore, there is no evolutionary reason to eliminate this defense mechanism even if it is harmful in old age.

---「11.
From “The Tug-of-War Between Microbes and the Immune System”

The most compelling evidence that the microbiome influences bone density comes from studies using probiotics and prebiotics.
That is, in mice, changes in the gut microbiome by probiotics such as Lactobacillus increased bone mass and suppressed estrogen-related bone loss.
Similar results have been obtained in humans.
The probiotic Lactobacillus reuteri increased blood vitamin D levels, promoting calcium absorption and bone health.
And when 417 elderly people with arm fractures were administered the probiotic Lactobacillus casei to some of them, the fractures healed faster in the administered group than in the non-administered group.

---「12.
From "Bend Your Microbiome: Muscles and Bones"

The fundamental shift in our living environment from an agricultural to an urban society has resulted in reduced contact with the microbial communities essential for the development of our body's immune system.
As a result, respiratory diseases are on the rise, with 300 million asthmatics worldwide and more than 40% of the population in developed countries suffering from allergies.
And studies have reported that several environmental factors that increase contact with microorganisms reduce the risk of developing asthma.
For example, children raised on Bavarian or Amish farms, where they have close contact with livestock, generally have a much lower incidence of asthma than children from non-farm areas.
Factors that reduce the incidence of allergic diseases include contact with animals at an early age, such as going to a stable or breastfeeding before the age of one, normal delivery, and not taking antibiotics in childhood.
---「13.
So clean, it's okay if it's a little dirty: From "Microorganisms around us"

Antibiotics are one of the greatest medical discoveries of the 20th century, miracle drugs that have saved countless lives.
Thanks to antibiotics, we live much longer than people did a century ago.
However, these antibiotics are causing new problems by affecting the microbial community.
More than 80% of antibiotics used in Canada and the United States are not used to treat disease, but are used in animal husbandry as growth promoters.
This use is already banned in Europe.
North America is also beginning to recognize this problem, with major fast-food companies like McDonald's, Subway, and Kentucky Fried Chicken now using antibiotic-free livestock and poultry.
In addition to the mass use of antibiotics for animal husbandry, unnecessary overprescription and overuse of antibiotics are leading to the emergence of antibiotic-resistant pathogens.
These 'super-resistant pathogens' are so difficult to treat that there are serious concerns worldwide that we are returning to the pre-antibiotic era.
As we have seen, more than 2 million people in the United States become infected with antibiotic-resistant bacteria each year, and at least 23,000 of them die.

---「14.
The Fountain of Youth is Full of Microbes!: Living with Our Body's Microbes

The past decade has been a renaissance in microbiology, with remarkable achievements in understanding the microbes in and around us, from the discovery that we co-evolved with them to the groundbreaking discovery that microbes are fundamentally involved in health and disease throughout our lives.
This new knowledge opens up a new era of possibilities for exploiting the many beneficial capabilities of microbes for human health.

---「14.
The Fountain of Youth is Full of Microbes!: Living with Our Body's Microbes