The Cancer Research
There is strong evidence that eating high amounts of red meat increases the risk of colorectal cancer.
There is strong evidence that consuming Red Meat (Beef, Pork, Lamb): Increases Risk of Colorectal Cancer INCREASES the risk of:
- Colorectal Cancer
Interpreting the data
After a systematic review of the global scientific literature, AICR/WCRF analyzed how foods and their nutrients affect the risk of developing cancer.
“Convincing” or “probable” evidence means there is strong research showing a causal relationship to cancer—either decreasing or increasing the risk. The research must include quality human studies that meet specific criteria and biological explanations for the findings.
A convincing or probable judgement is strong enough to justify recommendations.
· There is probable evidence that red meat (Beef, Pork, Lamb) INCREASES the risk of:
- Colorectal cancer
“Limited suggestive” evidence means results are generally consistent in overall conclusions, but it’s rarely strong enough to justify recommendations to reduce risk of cancer.
- Limited evidence suggests that processed meat may INCREASE the risk of:
- Lung, pancreatic, and nasopharyngeal cancers.
Ongoing Areas of Investigation
- Research Update
Evidence is strongest linking high consumption of red meat with greater risk of colorectal cancer. Several mechanisms could account for this increased risk, and more research is needed to better understand the role of each in cancer development:
- Red meat is higher than poultry or seafood in heme iron. This particular form of iron can lead to the production of free radicals that damage DNA and promote the formation of nitroso compounds, which can create damage within the gut that leads to cancer.
- Cooking meat at high temperatures, and smoking or grilling meat, can produce other cancer-causing compounds called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). These compounds are not unique to red meat, however, so alone they do not explain the difference in risk from red meat compared to poultry and seafood.
- Emerging evidence suggests that red meat may also increase cancer risk by promoting chronic, low-grade inflammation. Eating habits that include high amounts of red meat seem to affect the bacteria that live in the gut (the gut microbiome), increasing microbes that can promote inflammation.
- Research is underway to investigate whether other choices that make up overall eating habits, such as fiber-rich foods and vegetables with protective phytochemicals, might lessen the risk of red meat consumption. Although theoretically possible, the evidence is lacking for now.
Although single studies occasionally make headlines linking red meat with greater risk of breast or prostate cancer, analysis of overall research shows only potential trends that involve a lot of inconsistencies that need to be better understood.
AICR/WCRF also found limited evidence suggesting a possible association with red meat and greater risk of cancers of the nasopharynx, lung and pancreas. The AICR/WCRF expert panel evaluated the evidence and found it too limited to support a dietary recommendation, however.
*After a systematic review of the global scientific literature, AICR/WCRF analyzed how red meat affects the risk of developing cancer.
- Evidence categorized as “convincing” and “probable” means there is strong research showing a causal relationship to cancer—either decreasing or increasing the risk. The research must include quality human studies that meet specific criteria and biological explanations for the findings.
- A convincing and probable judgment is strong enough to justify recommendations.
- Evidence categorized as “limited suggestive” means results are generally consistent in overall conclusions, but it’s rarely strong enough to justify recommendations to reduce the risk of cancer.
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References
- World Cancer Research Fund / American Institute for Cancer Research. Continuous Update Project Expert Report 2018. Diet, nutrition, physical activity and colorectal cancer. Available at: dietandcancerreport.org.
- IARC Working Group. Volume 114: Consumption of red meat and processed meat. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Lyon; 6–13 September, 2015.: International Agency for Research on Cancer,.
- Hammerling U, Bergman Laurila J, Grafström R, Ilbäck N-G. Consumption of Red/Processed Meat and Colorectal Carcinoma: Possible Mechanisms Underlying the Significant Association. Crit Rev Food Sci Nutr. 2016;56(4):614-634.
- Turesky RJ. Mechanistic Evidence for Red Meat and Processed Meat Intake and Cancer Risk: A Follow-up on the International Agency for Research on Cancer Evaluation of 2015. CHIMIA International Journal for Chemistry. 2018;72(10):718-724.
- Fonseca-Nunes A, Jakszyn P, Agudo A. Iron and Cancer Risk—A Systematic Review and Meta-analysis of the Epidemiological Evidence. Cancer Epidemiology Biomarkers & Prevention. 2014;23(1):12-31.
- Norat T, Scoccianti C, Boutron-Ruault MC, et al. European Code against Cancer 4th Edition: Diet and cancer. Cancer Epidemiol. 2015;39 Suppl 1:S56-66.
- O’Keefe SJ. Diet, microorganisms and their metabolites, and colon cancer. Nat Rev Gastroenterol Hepatol. 2016;13(12):691-706.
- Tuan J, Chen YX. Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks. Gastrointestinal Tumors. 2016;3(1):17-24.
- Frugé AD, Smith KS, Riviere AJ, et al. Primary Outcomes of a Randomized Controlled Crossover Trial to Explore the Effects of a High Chlorophyll Dietary Intervention to Reduce Colon Cancer Risk in Adults: The Meat and Three Greens (M3G) Feasibility Trial. Nutrients. 2019;11(10):2349.
- World Cancer Research Fund/American Institute of Cancer Research. Continuous Update Project Expert Report 2018. Meat, fish and dairy products and the risk of cancer. Available at: dietandcancerreport.org.
- Norat T, Chan D, Vingeliene S, et al. The Associations Between Food, Nutrition and Physical Activity and the Risk of Breast Cancer. WCRF/AICR Systematic Literature Review Continuous Update Project Report. London: World Cancer Research Fund / American Institute for Cancer Research;2017.
- Norat T, Vieira AR, Chan D, et al. The Associations Between Food, Nutrition and Physical Activity and the Risk of Prostate Cancer. WCRF/AICR Systematic Literature Review Continuous Update Project Report. London: World Cancer Research Fund / American Institute for Cancer Research;2014.
- Wu J, Zeng R, Huang J, et al. Dietary Protein Sources and Incidence of Breast Cancer: A Dose-Response Meta-Analysis of Prospective Studies. Nutrients. 2016;8(11):730.
- Wu K, Spiegelman D, Hou T, et al. Associations between unprocessed red and processed meat, poultry, seafood and egg intake and the risk of prostate cancer: A pooled analysis of 15 prospective cohort studies. International Journal of Cancer. 2016;138(10):2368-2382.
