This book illuminates "the remote effect of the gut on our central nervous system, the brain, and provides possible pathophysiological explanations for many chronic diseases whose causes were previously unknown."

This book describes "how bacteria, fungi, and allergies influence the nervous system."

2.2 million people in Europe suffer from chronic inflammatory bowel diseases such as ulcerative colitis and Crohn's disease. Depression and neurodegenerative diseases such as Parkinson's, Alzheimer's, and multiple sclerosis are increasingly being diagnosed in younger patients as well. This book describes the massive communication between the nerve cells in the gut (the second brain) and the brain.

This book is aimed at physicians as well as interested laypeople and those affected – especially everyone suffering from irritable bowel syndrome, digestive disorders, and mental illnesses.