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Alanna Collen. 10% Human: How Your Body’s Microbes Hold the Key to Health and Happiness
10% Human. How Your Body’s MicrobesHold the Key to Healthand Happiness. ALANNA COLLEN
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Dedication
PROLOGUE. Being Cured
INTRODUCTION. The Other 90%
A simplified tree of life, showing the three domains and four kingdoms of Domain Eukarya
The human gut
ONE. Twenty-First-Century Sickness
TWO. All Diseases Begin in the Gut
The gut lining
THREE. Mind Control
FOUR. The Selfish Microbe
A history of planet Earth
The evolution of mitochondria
FIVE. Germ Warfare
SIX. You Are What They Eat
Schematic of the workings of GPR43 locks and SCFA keys
SEVEN. From the Very First Breath
EIGHT. Microbial Restoration
CODA. Twenty-First-Century Health
Societal Changes
Individual Changes
EPILOGUE. 100% Human
Picture Section
Smallpox was common even in developing countries until the 1900s. This man was photographed around the turn of the century
Parting the sparse feathers on the underside of a garden warbler (top) reveals the large energy reserves stored as fat following binge eating and a metabolic shift in preparation for migration, in comparison to a lean garden warbler (bottom) without these fat reserves
A mutation in the gene for the hormone leptin leads to genetically obese (ob/ob) mice, which are around three times the weight of their lean littermates
The prevalence of obesity (defined as a BMI of 30kg/m2 or more) has increased significantly over time, as shown by these maps of data collected by America’s Centers for Disease Control’s Behavioral Risk Factor Surveillance System. In 2012, 35 per cent of American adults and 17 per cent of children were obese. A further 34 per cent of adults and 15 per cent of children were overweight, but not obese
Ellen Bolte with Andrew and his older sister Erin on Christmas Day 1993, shortly after Andrew developed autism
Despite lacking a background in biology, Ellen Bolte was compelled to investigate the possible microbiological causes of autism in her son Andrew as a toddler. The Bolte family in 2011 – (from left to right) Andrew, Ellen, Erin and Ron
An ant in Papua New Guinea that has succumbed to the behaviour-controlling fungus, Cordyceps, which compels it to climb a tree and bite into the central vein of a leaf before it dies, scattering fungal spores over the forest floor
A parasitic trematode worm has evolved to cause limb abnormalities in American frogs, easing its transmission into its next host, the heron, where it continues its life cycle. Its efforts are supported by the contamination of wetlands with pesticides
Male greater sac-winged bats entice females by wafting a microbially-refined perfume over them as they roost
The perfume is carefully blended by allowing a precise community of microbes to ferment a mixture of urine, saliva and semen within specialised pouches on the wings
Using Robogut at the University of Guelph, Canada, graduate student Erin Bolte is testing her mother Ellen’s hypothesis that the microbes of the gut can be responsible for autism
‘Bubble boy’ David Vetter suffered from the inherited disease Severe Combined Immunodeficiency and lived in an isolation bubble from his birth in 1971 to his death in 1984. He is the closest a human has come to living germ-free
The release of the antibiotic penicillin to the public at the end of the Second World War meant an end to previously incurable infectious diseases, such as gonorrhoea
The caecum – an area of the gut usually densely populated with microbes – is grossly over-sized in germ-free mice (left) compared to normal mice (right). The reason for this dramatic anatomical difference is unclear
Mice fed a high-fat diet have a greater fat mass than those on a normal diet, but adding a daily low dose of the antibiotic penicillin from the start of life amplifies the effect of the high-fat diet, making the mice gain even more fat tissue
Transferring the gut microbes of mice treated with low dose penicillin from early in life into lean, germ-free mice results in weight gain in the recipient mice. The transfer of microbes from an untreated control mouse does not
Anne Miller was the first person to be saved by penicillin, after she became critically ill with an infection following a miscarriage. Here, she stands with Sir Alexander Fleming (right) and an unidentified man in 1942, after her recovery
Modern Western supermarkets are filled with boxes of processed and preserved food that is barely identifiable as either animal or plant, and is often far lower in fibre than its source
Koala joeys do not have the genes necessary to digest eucalyptus leaves. By eating faecal ‘pap’ produced by their mothers, they build a colony of microbes that break down fibrous plant material for them
After hatching, Kudzu bugs consume packages of microbes left by their mother next to the egg cases. If the packages are missing, the bugs wander in search of them
After a road accident, Peggy Kan Hai had surgery on her foot and developed a life-threatening antibiotic-resistant Clostridium difficile infection in her gut. She recovered after a faecal microbiota transplant from her husband
Gastroenterologist Professor Tom Borody at the Centre for Digestive Diseases in Australia advertises to recruit stool donors for a clinical trial of faecal microbiota transplants in patients with inflammatory bowel disease
Volunteers donating to Massachusetts-based stool bank OpenBiome save lives and earn money for each donated stool
OpenBiome staff member Mary Njenga processing donated faecal samples to send to C. diff patients in hospitals and clinics across the United States for faecal microbiota transplantation
Volunteers wishing to donate stool to OpenBiome are screened for microbiota-related health problems, including obesity, allergies, autoimmune diseases and mental health problems. Only a small proportion of volunteers are eligible to have their stool processed as a faecal microbiota preparation
REFERENCES
Introduction
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Coda
LIST OF ILLUSTRATIONS
INDEX
ACKNOWLEDGEMENTS
About the Publisher
Отрывок из книги
For Ben and his microbes.
My favourite superorganism.
CARL SAGAN
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The colon, which forms most of the length of the large intestine, running up the right-hand side of your torso, across your body under your rib cage, and back down the left-hand side, provides homes for microbes, numbering one trillion (1,000,000,000,000) individuals per millilitre by now, in the folds and pits of its walls. Here, they pick up the scraps of our food and convert them into energy, leaving their waste products to be absorbed into the cells of the colon’s walls. Without the gut’s microbes, these colonic cells would wither and die – whilst most of the body’s cells are fed by sugar transported in the blood, the colonic cells’ main energy source is the waste products of the microbiota. The colon’s moist, warm, swamp-like environment, in parts completely devoid of oxygen, provides not only a source of incoming food for its inhabitants, but a nutrient-rich mucus layer, which can sustain the microbes in times of famine.
Because HMP researchers would have to cut open their volunteers to sample the different habitats of the gut, a far more practical way of collecting information about the gut’s inhabitants was to sequence the DNA of microbes found in the stool. On its passage through the gut, the food we eat is mostly digested and absorbed, both by us and our microbes, leaving only a small amount to come out the other end. Stool, far from being the remains of our food, is mostly bacteria, some dead, some alive. Around 75 per cent of the wet weight of faeces is bacteria; plant fibre makes up about 17 per cent.
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