Protective effect of the "food-microorganism-SCFAs" axis on colorectal cancer: from basic research to practical application.

Background: Recent studies have shown that the short-chain fatty acids (SCFAs) produced by the gut microbiota play a positive role in the development of colorectal cancer (CRC).

Aims: This study aims to elucidate the "food-microorganism-SCFAs" axis and to provide guidance for prevention and intervention in CRC.

Methods: The PubMed, Embase and Cochrane databases were searched from their inceptions to August 2018, and 75 articles and 25 conference abstracts were included and analysed after identification and screening.

Results: The concentrations of SCFAs in CRC patients and individuals with a high risk of CRC were higher than those in healthy individuals. The protective mechanism of SCFAs against CRC has been described in three aspects: epigenetics, immunology and molecular signalling pathways. Many food and plant extracts that were fermented by microorganisms produced SCFAs that play positive roles with preventive and therapeutic effects on CRC. The "food-microorganism-SCFAs" axis was constructed by summarizing the pertinent literature.

Conclusions: This study provides insight into the basic research and practical application of SCFAs by assessing the protective effect of SCFAs on CRC.