Processed meat and colorectal cancer: a review of epidemiologic and experimental evidence.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing epidemiological and experimental mechanistic studies without systematic review methodology.
PubMed 18444144 · doi:10.1080/01635580701684872
What was done
This narrative review synthesized published epidemiological and experimental literature evaluating the relationship between processed meat consumption and colorectal cancer etiology. It examined risk estimates and evaluated four primary experimental hypotheses: high-fat promotion via insulin resistance or fecal bile acids, heterocyclic amines and polycyclic aromatic hydrocarbons from high-temperature cooking, dietary and endogenous N-nitroso compound formation, and heme iron promotion of mucosal cell proliferation via lipoperoxidation or fecal water cytotoxicity.
What was found
Epidemiologic studies reported a 20% to 50% excess risk of colorectal cancer in the highest intake category of processed meat compared to non-eaters. The excess risk per gram of intake was reported to be clearly higher than that of fresh red meat. Experimental evidence suggested that nitrosation may increase the toxicity of heme iron in cured products.
Why it matters
Clarifying the specific carcinogenic mechanisms of processed meat may allow manufacturers to alter curing and processing methods to reduce cancer risk without requiring complete dietary avoidance.
Limits
As presented in the abstract, no systematic search criteria, meta-analytic pooling, or study count (n) are provided. Effect estimates lack confidence intervals. Furthermore, the mechanistic hypotheses rely largely on studies conducted on fresh red meat rather than processed meat specifically.
Cited by
- supports Nitrates added to processed meat form potentially carcinogenic compounds in the human gut to a significantly greater degree than unprocessed red meat.