Relationships between gut microbiota, red meat consumption and colorectal cancer

Excessive consumption of red and processed meat has been associated with a higher risk of developing colorectal cancer. There are many attempts to explain the risk of colorectal cancer associated with the consumption of red and processed meat: The temperature cooking of meat such as grilling and smoking contribute to the formation of mutagenic compounds including heterocyclic amines and polycyclic aromatic hydrocarbons.Heme iron in red meat is involved in the formation of N-nitroso compounds and lipid peroxidation products in the digestive tract.Fatty red meat is involved in the production of secondary bile acids by the bacteria of the gut microbiota. Many of the products formed are genotoxic and can cause DNA damage and initiate carcinogenesis of colorectal cancer. Various mechanisms contributing to their genotoxic role have been established in human and animal studies. In addition, there is increasing evidence that compounds formed from red and processed meat interact with the gut microbiota in colorectal cancer pathways. Although several early studies in animals and humans suggest a direct causal role of the gut microbiota in the development of colorectal cancer, the links between diet, gut microbiota, and colonic carcinogenesis are largely associations rather than proven causal relationships. Various biological mechanisms, including inflammation and oxidative stress can lead to DNA damage, gut dysbiosis, and therefore increase the risk of colorectal cancer. Dysbiosis of the gut microbiota may increase the risk of colorectal cancer through dietary component promotion of colonic carcinogenesis. In this paper, we review and update current knowledge about the relationships between red meat consumption, gut microbiota, and colorectal cancer.