Although it is well known that our intestinal microbiota plays an important role in health and disease, it is often difficult to study the precise role of the human intestinal microbiota. This is largely due to the difficulties of studying the human intestinal microbiota, e.g., its very complex composition, huge number of constituents, active metabolic activities, the very special conditions in our intestinal tract including its strict anaerobic condition and low redox potential. It is also difficult to study the human intestinal microbiota in humans due to the difficulties in controlling genetic, environmental and dietary conditions of humans and due to ethical problems associated with utilizing pathogens, carcinogens or toxic substances in human volunteers. Thus, studying our intestinal microbiota requires special techniques. In this review, examples of
in vitro and
in vivo models to study the ecology and roles of human intestinal microbiota and their advantages and disadvantages are discussed.
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