Meat and Colorectal Cancer: Associations and Issues

Epidemiologic studies indicate an association of modest strength between consumption of red meat and colorectal cancer risk. Candidate compounds in red meat implicated in this association include those derived from processing (heterocyclic aromatic amines [HAAs], polycyclic aromatic hydrocarbons [PAHs], and N-nitroso compounds [NOCs]), as well as heme. Questions regarding HAAs and PAHs as etiological agents include their low concentration in meat relative to high concentrations in experimental studies and differing colorectal associations between different HAA and PAH food sources. The role of added nitrite and nitrate meat preservatives in NOC formation, as well as the potential inhibitory effect of calcium on heme-stimulated NOC formation remain uncertain and warrant further investigation. Improvements in dietary exposure assessment methods for the exogenous compounds and a greater understanding of gene–diet interactions will be necessary to clarify the role of meat mutagens and to more firmly establish the relationship between meat consumption and colorectal cancer.