Epidemiology, Molecular Mechanisms, and Clinical Trials: an Update on Research on the Association Between Red Meat Consumption and Colorectal Cancer.

PURPOSE OF THE REVIEW: Colorectal cancer is the second most common cause of cancer death in the world. The aim of this review is to provide an update on recent epidemiological studies, the molecular mechanisms involved, and ongoing clinical trials investigating the relationship between red meat consumption and colorectal cancer.

RECENT FINDINGS: Evidence in the literature proposes an association between red meat consumption and development of colorectal cancer, and there is some insight with regard to the mechanisms involved. Twenty studies of the IARC report (1990-2015) showed that red meat is positively associated with colorectal cancer whereas 14 studies either supported no positive association or no statistically significant association between red meat consumption and risk for CRC. More recent epidemiological studies conducted from 2016 and onwards provided further evidence that adherence to diets low in red and/or processed meat reduces the risk of colorectal cancer. Evidence from recent studies supports that quantity, doneness, and preparation of red meat play a role in colorectal carcinogenesis. Red meat's degradation products allow for the creation of a pro-inflammatory colonic microenvironment, and the gut microbiome plays a role in colorectal carcinogenesis. Heme, hydrogen sulfide, lipid peroxidation, nitroso compounds, and the bacterium Fusobacterium Nucleatum (as well as possibly other bacteria such as Akkermansia muciniphila, Eubacterium cylindroides, Eubacterium eligens 1 and 2, and Eubacterium rectale 1 and 2) also partake in the process of colorectal carcinogenesis. Several clinical trials are underway investigating the effects of different diets and red meat substitution products on colorectal cancer incidence as well as the underlying molecular mechanisms involved in the process.