The human intestine harbors over 100 species of bacteria with a total of approximately 100 trillion bacterial cells, creating a complex intestinal microbiota. Studies in recent years have revealed that intestinal microbiota form various volatile substances and are thought to be linked to health or disease. Some of the metabolites produced by intestinal microbiota are constantly absorbed from the intestinal lumen and transported throughout the entire body. In recent years, it has become clear that the intestinal microbiota contributes to the preservation and promotion of the hosts’ health and attention has been focused on the relationship of the intestinal microbiota and metabolites with health and diseases. For this reason, it is extremely important to analyze the metabolites produced by the intestinal microbiota.
This has raised the attention on researches regarding the intestinal microbiota. In the field of foods, there are studies aiming to verify the health effects of lactic acids in functional foods.