Hydrogen sulfide is a trace gas signaling molecule that is metabolized in the gut by intestinal epithelial cells or intestinal microbiota using cysteine as its substrate. More and more studies have confirmed that patients with colorectal cancer are accompanied by gut flora disturbance and an increase in the level of hydrogen sulfide synthesis in the body. The pathway of hydrogen sulfide production and its physiological and pathological effects in colorectal cancer were reviewed in the present paper. The value of exhaled hydrogen sulfide in screening and early prediction of colorectal cancer as a novel target was also discussed.

In recent years, postbiotics, a new concept related to probiotics, has been used to describe some certain inactivated microorganisms or sterile extracts, which may provide host health benefits through distinct biological activities from those of probiotics. A series of studies have shown that some postbiotics have anti-inflammatory, immunomodulatory, antioxidant and antibacterial activities, which have been used in the adjuvant treatment of metabolic syndrome, anxiety, depression, and even corona virus disease 2019, although their mechanisms and the signaling pathways involved have not been fully elucidated. With the deepening of the research and development of postbiotics, it is expected to be widely used in the healthy food industry and medical health care field in the future.

The human body and the gut microbiota are mutually beneficial and symbiotic under normal conditions. The gut microbiota has been proven to be associated with various diseases, and the liver, as a neighboring organ, is closely related to the gut both anatomically and functionally. Numerous studies have shown that the composition of gut microbiota undergoes significant changes when suffering from liver disease and the changes can significantly affect the development of liver diseases. This review summarizes the changes in gut microbiota and its metabolites under different liver disease states and their impact on the occurrence and development of liver disease to help colleagues deeply understand the relationship between the changes in gut microbiota and the development of liver disease, and then jointly explore new strategies for the prevention and treatment of liver disease based on gut microbiota.

The gut microbiota-host metabolic axis is defined as a group of high-speed multi-disciplinary, interactive chemical signal pathways that link a specific host cell pathway to a series of gut microbiome species, subecosystems and metabolic activities. Many diseases are related to intestinal microbiota disorders (alterations of the composition or functions of the intestinal microbiota). The present article focus on the gut flora dysfunction classification, the causes and consequences of the dysfunction of intestinal metabolites, as well as their roles in the molecular etiology of various intestinal diseases. Meanwhile, novel diagnostic and therapeutic approaches targeting microbiota and its metabolites are also discussed.