By Tamzyn Murphy Campbell
BSc, BSc Med(Hons) Human Nutrition and Dietetics, RD
A recent release of the World Health Organization’s (WHO) summary paper on the carcinogenicity of eating red and processed meat is a feast for media scaremongering. But did this paper find that all red meat causes cancer? Are media reports accurate? And is there more to the story?
In 2007 the World Cancer Research Fund and American Institute for Cancer Research (WCRF/AICR) report judged that the evidence linking red and processed meat to colorectal cancer was convincing. However, a subsequent review study – which happened to be funded by the meat industry – claims that these organisations did not have sufficient evidence to make that conclusion. While most recent study conclusions support the WCRF/AICR report’s warning, this industry-funded study did have a valid point, in that many studies grouped processed and red meats together, making identification of the true culprit rather difficult. So, the World Health Organization’s (WHO) summary paper on the carcinogenicity of eating red and processed meat comes at the perfect time to lay the debate to rest. The WHO has rated processed meat (e.g. hot dog sausages and bacon) a group 1 carcinogen (i.e. it causes cancer) – no surprises there – and red meats (including beef, lamb and pork) group 2A carcinogens (i.e. it probably causes cancer). The relationship between red and processed meats and other cancers remains unclear .
Researchers think that red and processed meat’s colorectal cancer-causing effects may be due various factors. Carcinogenic compounds are formed within meat when it’s cooked at high temperatures, called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). , Cancer-causing N-nitroso compounds, found in processed meat and produced within the colon when red meat (or more specifically heam) is eaten, may also contribute to the cancer link. [2,1] It is possible that haem iron itself contributes to cancer formation by acting as a cell and DNA-damaging free radical. However, when it comes to red meat and it’s probably colon cancer risk it’s important to bear in mind that the dose makes the poison (eating unprocessed red meat two to three times a week will likely pose little risk). Also, eating red meat in combination with green leafy vegetables (specifically the chlorophyll contained therein) may protect you against the carcinogenic effects of heme iron within the colon .
For a detailed critique on the WHO summary paper read: Patel K. Scientists just found that red meat causes cancer… or did they? Examine.com. 27 Oct 2015
 Pan A, Sun Q, Bernstein AM, et al. Changes in red meat consumption and subsequent risk of type 2 diabetes mellitus: three cohorts of US men and women. JAMA Intern Med. 2013 Jul 22;173(14):1328-35.http://www.ncbi.nlm.nih.gov/pubmed/23779232
 Balder HF, Vogel J, Jansen MC, et al. Hene and chlorophyll intake and risk of colorectal cancer in the Netherlands cohort study. Cancer Epidemiol Biomarkers Prev 2006 Apr;15(4):717-25