Information sheet: Meat and cancer

From National Cancer Control Policy
Obesity > Information sheet: Meat and cancer

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Information sheet: Meat and cancer



Key messages and recommendations

  • The term ‘meat’ encompasses a variety of foods, including unprocessed red meat (beef, veal, pork and lamb), processed meat, poultry and fish.
  • Processed meat is meat that has been smoked, cured, salted or contains added preservatives. This includes frankfurts (hot dogs), salami, chorizo, cabanossi, kransky, corned beef, pepperoni, pastrami, bacon and ham.
  • There is strong evidence that eating processed meat is linked to bowel cancer. As well, processed meat can be high in fat and salt. We recommend limiting processed meat consumption.
  • There is strong evidence that red meat is linked to an increased risk of bowel cancer. We recommend if you eat red meat, eat moderate amounts.
  • Lean red meat in moderation can be an important contributor to dietary iron, zinc, vitamin B12 and protein in the Australian diet.
  • There is insufficient evidence to draw any conclusions on poultry intake and cancer risk.
  • For fish consumption, there is limited suggestive evidence that it may be linked to a reduced risk of liver and bowel cancer. There is strong evidence that consuming Cantonese-style salted fish increases the risk of nasopharyngeal cancer. There is strong evidence that consuming foods preserved by salting (including pickled vegetables and salted or dried fish, as traditionally prepared in East Asia) increases the risk of stomach cancer.
  • Meat is sometimes fried, grilled or barbecued at very high temperatures. Care should be taken when using these methods as it may affect the chemical composition as well as the nutritional value of the meat.
  • Cancer Council recommends:
    • Moderate consumption of unprocessed lean red meat can be part of a healthy diet. A moderate amount of meat is no more than 455g cooked red meat (equal to about 700g raw meat) per week. This could be a small 65g serve of cooked meat each day or 2 serves (130g) 3-4 times a week;
    • Limiting or avoiding processed meats such as frankfurts, salami, bacon and ham;
    • Limiting consumption of burnt or charred meat; and
    • Choosing lean cuts of meat and chicken and eating more fish and plenty of plant based foods such as fruit, vegetables, legumes/beans and wholegrain cereals.

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Background

The term ‘meat’ encompasses a variety of foods, including unprocessed red meat, processed meat, poultry and fish. Unprocessed red meat generally includes beef, veal, pork, goat, mutton and lamb, and processed meat refers to smoked, cured and salted meats (such as frankfurts, salami, bacon and ham), and canned meats. Processed meat is sometimes referred to as preserved meat. Processed meat differs from unprocessed red meat, in that it may be cured with the addition of preservatives (salt, nitrite or smoke) and/or other additives (phosphate, glutamate or ascorbic acid).

The Australian Dietary Guidelines provide recommendations for meat and poultry, grouped along with fish, eggs, tofu, nuts, seeds and legumes[1]. The guidelines recommend limiting red meat consumption to 455g of cooked lean red meat (600-700g raw) each week. This equates to a small 65g serve each day or a larger portion 3-4 times per week[1]. Additionally, the guidelines recommend limiting consumption of foods high in saturated fat, added sugar and salt, including processed meats[1].

Lean red meat is an important source of dietary iron, zinc, vitamin B12 and protein in the Australian diet. However, epidemiological evidence suggests that there is a relationship between red and processed meats, and cancer risk. The World Cancer Research Fund Continuous Update Project concludes that there is strong convincing evidence that consuming processed meat increases the risk of bowel cancer and strong evidence that consuming red meat is probably a cause of bowel cancer[2]. The World Health Organization International Agency for Research on Cancer has classified processed meats as a Group 1 Carcinogen, meaning there is sufficient evidence of carcinogenicity in humans. Additionally, red meat was classified as a Group 2A carcinogen, based on limited evidence from epidemiological studies showing positive associations between eating red meat and cancer[3]. An Australian study estimated that 17.8% of bowel cancers diagnosed in 2013 were attributable to the consumption of red and processed meat[4].

There is strong evidence that consumption of Cantonese-style salted fish is probably a cause of nasopharyngeal cancer[2].

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Biological mechanism

The following hypotheses have been proposed to explain the association between meat consumption and cancer risk, particularly bowel cancer:

  • Heterocyclic amines and polycyclic aromatic hydrocarbons form when meats are cooked at high temperatures and exposed to heat for prolonged periods[5]. These substances have been associated with bowel cancer[6][7].
  • Red meat and processed meat contain haem iron, which may stimulate the formation of carcinogenic N-nitroso compounds hence inducing tumorigenesis.*Processed meat also contains added N-Nitroso compounds, which have carcinogenic potential[2].
  • Fish, particularly those high in omega-3 polyunsaturated fatty acids, may be protective against bowel cancer as these fatty acids have been shown to reduce cell proliferation, probably by modifying the inflammatory response[6].

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Epidemiological evidence

Epidemiological evidence on the association between meat and cancer is summarized in the World Cancer Research Fund, Continuous Update Project Expert Report 2018. The primary findings on the strong evidence for processed and red meat and bowel cancer are highlighted below[2].

  • A meta-analysis of eight studies found that the risk of developing bowel cancer is 1.12 times higher for those who eat 100 grams of red meat per day compared to those who eat none. The conclusion was that there was a probable increase risk of bowel cancer associated with red meat consumption.
  • A meta-analysis of ten studies found that the risk of developing bowel cancer is 1.16 times higher for those who eat 50 grams of processed meat per day compared to those who eat none. There was convincing evidence of an increased risk of bowel cancer associated with processed meat consumption.
  • The average risk for an Australian adult for developing bowel cancer by the age of 75 in Australia is 4%.

In addition, there was limited suggestive evidence that red meat may be associated with an increased risk of nasopharynx, lung and pancreatic cancer, and processed meat with nasopharynx, oesophageal, lung, stomach and pancreatic cancer.

Other meats and cooking types

There was insufficient evidence to draw any conclusions on poultry and egg intake and cancer risk.

For fish consumption, there is limited suggestive evidence that it may be linked to a reduced risk of liver and bowel cancer. There is strong evidence that consuming Cantonese-style salted fish increases the risk of nasopharyngeal cancer. There is strong evidence that consuming foods preserved by salting (including pickled vegetables and salted or dried fish, as traditionally prepared in East Asia) increases the risk of stomach cancer.

For foods containing haem iron, there is limited suggestive evidence that it may be associated with an increased risk of bowel cancer.

There is limited suggestive evidence that the consumption of grilled or barbequed meat and fish increases the risk of stomach cancer.

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Current consumption levels

The 2011–2012 National Nutrition and Physical Activity Survey (NNPAS) reported that seven out of ten Australians consumed meat, poultry and game products and dishes the day before the survey[8]. On average, Australians consumed 1.7 serves of lean meats and alternatives per day, and 14% of people met the recommended daily number of serves of lean meats and alternatives. Red meat including beef, veal, lamb, pork and kangaroo contributed the largest proportion (38%), with poultry making up 29%, followed by nuts and seeds (11%), fish and seafood (9.9%), eggs (6.2%) and legumes (4.8%). The weekly consumption of red meat by Australians was estimated at an average 565 g – 24% higher on average than maximum suggested by the Guidelines. The age group with the highest total consumption of red meat was 14-18 year olds who averaged 625 g per week. For processed meats, an average of 0.4 serves was consumed daily, with 14-18 year old males having the highest intake of 0.6 serves on a given day[9].

Compared with data from the 1995 National Nutrition Survey, consumption of meat appears to have decreased. In 1995, most adults (85% of men and 77% of women) ate some meat, poultry or game on the day of the survey[10]. Between 1983 and 1995, mean daily intake of red meat and pork declined for both men and women; whereas mean daily intake of poultry and seafood increased[11].

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Dietary recommendations

Cancer Council recognises that red meat is an important contributor to dietary iron, zinc, vitamin B12 and protein in the Australian diet.

Cancer Council recommends people:

  • Can consume moderate amounts of unprocessed (or fresh) lean red meat. A moderate amount of meat is no more than 455g cooked red meat (equal to about 700g raw meat) per week. This could be a small 65g serve of cooked meat each day or 2 serves (130g) 3-4 times a week. This would be approximately ½ cup lean mince, two small chops or two slices of roast meat. Other substitutes for a serve of meat include 65–100 g cooked chicken, 80–120 g cooked fish fillet, two small eggs, ⅓ cup cooked legumes (lentils, chickpeas, split peas, dried or canned beans) or ⅓ cup nuts. Those eating meat should also try to eat plenty of plant-based foods like fruit, vegetables, legumes/beans and wholegrain cereals, which are beneficial to health and the environment.
  • Limit or avoid processed meats, which are high in fat and salt. Processed meats include frankfurts (hot dogs), salami, chorizo, cabanossi, kransky, corned beef, pepperoni, pastrami, bacon and ham.In Australia, fresh sausages are not permitted by the Food Standards Code to contain nitrate or nitrite. This is why we do not include sausages as an example of processed meat. Sausages vary in their composition, and may include cereals and other components. They may count as a meat serve if they are salt and fat reduced and made mostly from lean meat, or as a discretionary choice for regular sausages[1].
  • Choose lean cuts of meat and chicken.
  • Eat fish (preferably oily) at least two times per week.
  • Limit consumption of burnt or charred meat, and choose cooking methods such as casseroling, boiling or microwave heating over high-temperature grilling, pan-frying or barbequing, as while the evidence for an association between heterocyclic amines and cancer risk is inconsistent, there is reasonable doubt to permit cautionary advice.

These recommendations are consistent with the Australian Guide to Healthy Eating.

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Links


References

  1. 1.0 1.1 1.2 1.3
    Unable to find the reference "Citation:National Health and Medical Research Council 2013 4"
  2. 2.0 2.1 2.2 2.3
    Unable to find the reference "Citation:World Cancer Research Fund/American Institute for Cancer Research 2021"
  3. Unable to find the reference "Citation:Bouvard V, Loomis D, Guyton KZ, Grosse Y, Ghissassi FE, Benbrahim-Tallaa L, et al 2015 3"
  4. Unable to find the reference "Citation:Wilson LF, Antonsson A, Green AC, Jordan SJ, Kendall BJ, Nagle CM, et al 2017"
  5. Sinha R, Kulldorff M, Chow WH, Denobile J, Rothman N. Dietary intake of heterocyclic amines, meat-derived mutagenic activity, and risk of colorectal adenomas. Cancer Epidemiol Biomarkers Prev 2001 May;10(5):559-62 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/11352869.
  6. 6.0 6.1 Bingham SA. Epidemiology and mechanisms relating diet to risk of colorectal cancer. Nutr Res Rev 1996 Jan;9(1):197-239 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/19094271.
  7. Turesky RJ. Formation and biochemistry of carcinogenic heterocyclic aromatic amines in cooked meats. Toxicol Lett 2007 Feb 5;168(3):219-27 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/17174486.
  8. Unable to find the reference "Citation:Australian Bureau of Statistics 2014 6"
  9. Unable to find the reference "Citation:Australian Bureau of Statistics 2016 3"
  10. McLennan W, Podger A. National nutrition survey - foods eaten, Australia 1995. Canberra: Australian Bureau of Statistics; 1999. Report No.: 4804.0. Available from: http://www.ausstats.abs.gov.au/ausstats/subscriber.nsf/0/CA25687100069892CA256888001CD460/$File/48040_1995.pdf.
  11. Unable to find the reference "Citation:Baghurst K 1999"