Red and Processed Meats cause cancer – Dietary Guidelines – Missed opportunities to curb the cause of colorectal cancer
In the Q&A section of the 2015-2020 dietary guidelines, it is stated that the current guidelines integrated existing reports into its review, reports from the Institute of Medicine and the World Health Organization, among other international professional organizations and agencies (office of disease prevention and health promotion, 2016). However, on October 26, 2015, the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization (WHO), after reviewing over 800 studies linking red and processed meat to colorectal cancer, issued a press release stating that red and processed meats have been linked to cancer in humans (IARC, 2015). This press release was issued prior to the release of the 2015 -2020 dietary guidelines for Americans in December of 2015.
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The major goal of IARC, which is part of the WHO, is to identify the causes of cancer. The IARC has a rating system for classifying those items/substances that are, may be, or are not carcinogenic to humans. A quick review of the IARC monographs on the evaluations of carcinogenic risks to humans can provide you with the classification system. The classification system can be viewed here: http://monographs.iarc.fr/ENG/Classification/index.php.
|Group 1||Carcinogenic to humans|
|Group 2A||Probably carcinogenic to humans|
|Group 2B||Possibly carcinogenic to humans|
|Group 3||Not classifiable as to its carcinogenicity to humans|
|Group 4||Probably not carcinogenic to humans|
The WHO report has given processed meat a group 1 classification, meaning there is adequate evidence linking the consumption of processed meat to colorectal cancer (IARC, 2016). This same group 1 classification has also been given to tobacco in all forms (smoking, smokeless, and second hand smoke) as well as plutonium and asbestos (IARC, 2016). https://monographs.iarc.fr/ENG/Classification/ClassificationsGroupOrder.pdf.
The WHO report also recognized red meat as a probable carcinogen to humans and was given a Group 2A classification. The rationale for this classification is that more data needs to be acquired but according to the IARC (2015) red meat has “strong mechanistic evidence supporting a carcinogenic effect” (para. 2). The IARC (2015) press release further recognizes that an “association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer” (para. 3).
A 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18% (IARC, 2015, para. 6). To put that into context, three to four strips of bacon or one hot dog is approximately 50 grams. However bacon is not the only carcinogenic risk. Smoked meats, canned hams, processed lunch meats, and many other processed meats increase the risk of colorectal cancer (IARC, 2015).
The IARC (2015) refers to processed meat as:
Meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation. Most processed meats contain pork or beef, but processed meats may also contain other read meats, poultry, offal, or meat by-products such as blood (para. 11).
Examples of processed meats included by the IARC (2015) include “hot dogs (frankfurters), ham, sausages, corned beef, and bitlong or beef jerky as well as canned and meat based preparations and sauces” (para. 12). The report further goes on to explain what products are classified as red meat. The IARC (2015) report clarifies that red meat “refers to all types of mammalian muscle meat such as beef, veal, pork, lamb, mutton, horse, and goat” (para. 10).
The IARC’s 2015 press release can be viewed here:
The IARC’s journal article published in the lancet can be viewed here: http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(15)00444-1/abstract.
Previous to this report by the IARC branch of the WHO, the National Institute of Health (NIH) and National Cancer Institute’s (NCI), Cancer Trends Progress Report (2015) linked red and processed meat consumption to increased risk of colorectal cancer among other cancers such as prostate cancer (para. 1). The NIH (2015) defines red meat as “… beef, pork, and lamb, although some studies include all processed meats (such as bacon, sausage, hot dogs, and cold cuts) in their definition, regardless of animal origin” (para. 1). While continued research is needed to fully understand meat’s influence on cancer, there are multiple pathways by which cancer can develop after the ingestion of meat. According to the NIH (2015) “the increased risk may be explained by the iron and fat content in red meat, and/or the salt and nitrates/nitrites in processed meat. Additionally, when meat is cooked at high temperatures, substances are formed that may cause cancer” (para. 2). These possible cancer forming compounds are called heterocyclic amines and polycyclic aromatic hydrocarbons.
Despite available evidence from different governmental organizations within the United States and abroad, and over 800+ studies linking red and processed meat consumption to colorectal cancer and possibly prostate cancer, no mention or references were made in the 2015 – 2020 dietary guidelines for Americans. The bulk of evidence may not have been included in the United States Department of Health and Human Services and the United States Department of Agriculture (HHS and USDA) 2015 – 2020 Dietary Guidelines for Americans who co-authored the report along with many scientists in the field of nutrition. Yet, according to the office of disease prevention and health promotion’s Questions and Answers about the Dietary Guidelines (2016) website, “these reports summarize the most current and comprehensive evidence and have been written by a panel of recognized experts in the field” (p. 21).
According to the HHS and USDA (2015), the 2015-2020 United States Dietary Guidelines for Americans “a message from the secretaries” Thomas J. Vilsack and Sylvia M. Burrwell, recognize that “one of our government’s most important responsibilities is to protect the health of the American public.” And they continue, saying, “about half of all American adults—117 million people—have one or more preventable, chronic diseases, many of which are related to poor quality eating patterns and physical inactivity” (p. 7). Yet no mention of the WHO report on the link between red and processed meat consumption and colorectal cancer was included within the final draft of the 2015 – 2020 United States Dietary Guidelines for Americans, which are used to promote school lunch programs, school breakfast programs, nutrition programs for Women Infants and Children, as well as having a direct influence on the foods Americans purchase. However, the HHS & USDA (2015) report lists colorectal cancer as the second leading cause of cancer death within the U.S. and estimates that 1.2 million adult men and women have a history of colorectal cancer (p. 3). But there was no mention of the connection between red and processed meat and colorectal cancer.
While most organizations applauded the new 2015 – 2020 Dietary Guidelines, one organizations felt there was a missed opportunity to inform Americans about the dangers of red and processed meat consumption. Sampson and Rohloff (2016) of the American Cancer Society issued a statement on January 7, 2016 stating:
The 2015 Dietary Guidelines for Americans (Dietary guidelines) released today by the U.S. Department of Health and Human Services and the U.S. Department of Agriculture, do not acknowledge the totality of evidence available to make recommendations intended to reduce consumption of foods known to cause cancer (para. 1).
According to Sampson and Rohloff (2016) Dr. Richard Wender, Chief Cancer Control Officer of the American Cancer Society said, “the science on the link between cancer and diet is extensive. By omitting specific diet recommendations, such as eating less red and processed meat, these guidelines miss a critical and significant opportunity to reduce suffering and death from cancer” (para. 3).
Cancer Organizations and Recommendations
While processed meat has now been listed as a class 1 carcinogen and red meat as probably carcinogenic, some health organizations provide warnings against their consumption. The American Institute for Cancer Research (AICR) website uses some of the strongest language possible in terms of red and processed meat consumption. The AICR (2016a) cancer prevention guidelines state that Americans should “limit the consumption of red meats (such as beef, pork and lamb) and avoid processed meats” (para. 5). The AICR (2016b) further goes on to state that, “to reduce your cancer risk, eat no more than 18 ounces (cooked weight) per week of red meats, like beef, pork and lamb, and avoid processed meat such as ham, bacon, salami, hot dogs and sausages” (para. 2) The website also recognizes that even small portions of processed meat eaten daily increase one’s risk of colorectal cancer, and they also provide an example as a partial explanation as to the cause. According to the AICR (2016b), “heme iron, the compound that gives meat its color, has been shown to damage the lining of the colon” (para. 4).
The dietary guidelines for Americans are meant to provide the public with a healthy eating pattern. The public should be able to rely on one source of information for the most up to date health advice free from conflicts of interest. According to Herman (2010), the United States Department of Agriculture has a vested interest in selling agricultural products and at times tends to favor industry over the health of the general public (p. 285). While the guidelines cannot force the public to change their dietary habits, the public should be informed and provided with the best scientific evidence available. The guidelines should provide reliable and consistent data to inform the public of the optimal diet for health. The IARC (2015) determined that red meat is linked to cancer and processed meat is a cause of colorectal cancer while the HHS & USDA (2015) made no mention of this link, though they recognize colorectal cancer is the second leading cause of cancer death in the United States (p. 3).
Therefore, avoiding, abstaining or eliminating all sources of red and processed meat is advisable due to its link to colorectal cancer as well as the potential for increasing the risk of prostate and pancreatic cancer. However, cancer is not the only risk associated with consuming red and processed meat. The cholesterol, saturated fat, and trans-fat found in these and all other animal products has also been linked to increasing cardiovascular disease and type II diabetes. Therefore, to reduce the risk of developing cardiovascular disease, type II diabetes, and cancer, eliminating animal-based foods is an advisable goal (Estadella et al., 2013; Hopkins, 1992; Howell, McNamara, Tosca, Smith and Gaines, 1997; Institute of Medicine, 2002; Spence, Jenkins, Davignon, 2010).
American Institute for Cancer Research (2016) a. Recommendations for Cancer Prevention. Retrieved from http://www.aicr.org/reduce-your-cancer-risk/recommendations-for-cancer-prevention/.
American Institute for Cancer Research (2016) b. Recommendations for Cancer Prevention. Retrieved from
Bouvard, V., Loomis D., Guyton K. Z., Grosse, Y., Ghissassi F. E., Et. al. (2015). Carcinogenicity of consumption of red and processed meat. The Lancet Oncology, 16 (16), 1599-1600. Doi: http://dx.doi.org/10.1016/S1470-2045(15)00444-1 or http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(15)00444-1/abstract
Herman J. (2010). Food and Drug Law Journal Saving U.S. Dietary Advice from Conflicts of Interest. Retrieved from https://www.drmcdougall.com/misc/2010nl/jul/sc%20herman.indd.pdf
Hopkins P. N., (1992) Effects of dietary cholesterol on serum cholesterol; a meta-analysis and review. American Journal of Clinical Nutrition, 55. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/1534437,
Howell, W. H., McNamara, D. J., Tosca, M. A., Smith, B. T., Gaines J. A., (1997). Plasma lipid and lipoprotein responses to dietary fat and cholesterol: a meta-analysis. American Journal of Clinical Nutrition, 65. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/9174470,
International Agency Research on cancer, the cancer agency part of the the World Health Organization. (2015). IARC Monographs evaluate consumption of red meat and processed meat [Press release]. Retrieved from http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf
International Agency for Research on Cancer World Health Organization (2016, June 24). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Retrieved from http://monographs.iarc.fr/ENG/Classification/index.php.
National Academy of Sciences (2002, September 5). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Retrieved from http://www.nationalacademies.org/hmd/Reports/2002/Dietary-Reference-Intakes-for-Energy-Carbohydrate-Fiber-Fat-Fatty-Acids-Cholesterol-Protein-and-Amino-Acids.aspx
National Institute of Health National Cancer Institute Cancer Trends Progress Report (Last updated 2015, March). Red Meat Consumption Retrieved from http://progressreport.cancer.gov/prevention/red_meat#field_additional_information
Office of disease prevention and health promotion (2016, August 22). Questions and Answers About the Dietary Guidelines. Retrieved from Https://health.gov/dietaryguidelines/2015/qanda.asp#guidelines-q1
Sampson, D., & Rohloff, E., (2016, January, 7). American Cancer Society Cancer Action Network. New Dietary Guidelines disregard important link between diet and cancer; missed opportunity to reduce death and suffering. Retrieved from http://www.acscan.org/content/media-center/new-dietary-guidelines-disregard-important-link-between-diet-and-cancer-missed-opportunity-to-reduce-death-and-suffering/
Spence, J. D., Jenkins, D. J., Davignon, J., (2010) Dietary cholesterol and egg yolks: not for patients at risk of vascular disease. The Candian Journal of Cardiology, 26. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21076725
United States Department of Agriculture and the Department of Health and Human Services (2015, December). 2015 -2020 Dietary Guidelines for Americans Eighth Edition. Retrieved from https://health.gov/dietaryguidelines/2015/resources/2015-2020_Dietary_Guidelines.pdf
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