**10. Microbiome applications**

Studying the human microbiome is helping researchers to understand how the body responds to different diets, diseases and drugs. The human microbiome can be seen of as a source of genetic variety, a disease modifier, a significant component of immunology, and a functional entity that regulates metabolism and modulates drug interactions. On the one hand, there are numerous possible probiotics or helpful bacteria that could help to prevent or treat various diseases, albeit most of them are now unavailable for cultivation [79]. Little was known about the variety of microorganisms that happily dwell inside and on our bodies more than a decade ago, but researchers today believe they have the potential to influence the future of human health and examining linkages between health and disease. Almost 70% of the bacteria that make up the human microbiota are uncultivable, and many of them are anaerobic (so can only be cultivated without oxygen). These barriers have prompted researchers to investigate meta-genomics and in vivo models. While in vitro models of the digestive tract can be used to simulate one or more stages of digestion (in the stomach, small intestine, or colon), they are still incapable of duplicating the complexity of host-microbiota interactions [80]. Therefore the recent scientific evidence suggests that a healthy and diverse microbiome is beneficial to human health and the microbiome is becoming a cornerstone of preventive medicine (**Figure 6**).

**Figure 6.** *The microbiome can be used to study, diagnose and treat diseases.*
