When I began my studies at medical school in 1970, doctors viewed the body as a complex machine containing an infinite number of separate parts. On average, this machine works for seventy-five years, provided you take care of it and fuel it properly. Like a high-quality car, the body performs well, provided it is not subjected to major accidents, and no part is damaged or broken beyond repair. All that was expected of you was to undergo a few routine check-ups throughout your life to prevent any unexpected ailments. Medicine and surgery offered effective tools for treating serious health problems such as infections, emergency wounds, or heart diseases.
However, over the past forty to fifty years, something fundamental has gone wrong with our health, and the old model is no longer able to provide an explanation or solution for how to treat these problems. What is happening can no longer be easily explained by the presence of a single faulty organ or gene. Instead, we have begun to realize that the complex regulatory mechanisms that help our bodies and brains adapt to our rapidly changing environment are, in turn, affected by our changing lifestyles. These mechanisms do not work independently but as part of a whole. They regulate the quantities of food we consume, metabolism, body weight, our immune system, and the development and health of our brains. We are only just beginning to realize that the gut, the microbes that live within it – the gut microbiota – and the signaling molecules they produce from their vast number of genes – the microbiome – are key components of these regulatory systems.
In this book, I will offer a revolutionary new perspective on how the brain, the gut, and the trillions of microorganisms living in the gut communicate with each other. In particular, I will focus on the role these communications play in maintaining the health of our brain and gut. I will discuss the negative consequences for both organs resulting from the disruption of these conversations and suggest ways to achieve optimal health by restoring and improving the communication between the brain and the gut.