We are what they eat:
Interaction of the human microbiota with its host
The basic building block of the human body is the cell. Up to 100 trillion (1014) cells are organized into specialized tissues and organs which comprise the body systems that carry out the functions necessary for survival (e.g., digestive system, cardiovascular system, nervous system, immune system). However, only one tenth of “human” cells are human in origin. The remaining 90% of cells are composed of the microorganisms that colonize our bodies. The lion’s share of these organisms (collectively known as the microbiota) is the bacteria which reside in our gastrointestinal tract. From there, the microbiota exerts a tremendous influence on our body systems, tweaking them in a way that can have a great impact on our health and well-being.