Good or bad: gut bacteria in human health and diseases

The human gastrointestinal tract is estimated to be colonised by over 1014 bacteria, approximately 10-fold of the total number of cells in the human body. Recently, an important role of the gut microbiota composition in many areas, such as normal development, immune system maturation, CNS functions, has been discovered. Also, accumulating evidence suggests that gut bacteria play critical roles in maintaining human health in many aspects. Gut microbiota dysbiosis may lead to a number of diseases, including gastrointestinal disorders, obesity, cardiovascular diseases, allergy and central nervous system-related diseases. In this review, we propose that novel effective and safe therapy methods for human diseases based on modulation of gut microbiota would attract more attention from both scientists and clinicians.