In Defence of Liberty

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Saving our bacon

Photo illustration of bacon is fried up in a pan in a kitchen in Golden

Bacon is fried up in a pan in a kitchen in this photo illustration in Golden, Colorado, October 26, 2015. (Edited: REUTERS/Rick Wilking)

Processed meats and red meats, such as bacon and sausages, were classified as causing cancer in humans, by monographs from the International Agency for Research on Cancer (IARC) [1]. The IARC is part of the World Health Organisation.

Given the popularity of meat in the British diet, this announcement was met with derision and misrepresentation. For instance, the Yahoo! News article [2], written by Ellie Genower, screamed the headline: Bacon And Sausages As Big A Cancer Threat As Cigarettes, Say World Health Organisation.

This article was shared over 10,900 times, and was a rewriting of the Daily Mail article on the same subject.

Red meat is any meat which has a dark red colour prior to cooking, like beef, pork and lamb. Processed meats are not sold fresh, but have been preserved in some manner, suhc as cured, salted or smoked meats.

Strength of Evidence

Despite the terminology used in the headline, the IARC classifications are by the strength of the evidence, and not the degree of risk. It is the identification of a hazard, not a calculation of the risk. Group 1, which processed meats have been placed into [3], represents those items which are “carcinogenic to humans”. Group 2A lists those items found to be “probably carcinogenic to humans”, which now include red meats. The IARC studies the available evidence on how likely selected things are to cause cancer, not how many cancers could be considered as caused by these things.

These classifications do not determine the degree of cancerous risk associated with a particular activity, such as eating processed meat, nor do they prescribe any form of political or regulatory response, though an individual response may be recommended. As highlighted by Cancer Research UK [4], a 2011 analysis led by researchers at the School of Public Health at the Imperial College London [5], concluded:

High intake of red and processed meat is associated with significant increased risk of colorectal, colon and rectal cancers. The overall evidence of prospective studies supports limiting red and processed meat consumption as one of the dietary recommendations for the prevention of colorectal cancer.

What is important from this study is the estimates for the relative risk of colorectal cancer.

pone.0020456.g003

Non-linear dose-response meta-analysis of red and processed meats consumption and the risk of colorectal cancer. (Source: PLoS One)

For fresh red meat, a 100g per day increase in consumption was associated with a 17% increase in colorectal cancer incidence. The 95% confidence interval was between a 5% increase and a 31% increase. For processed meats, a 50g daily increase in consumption was associated with a 18% increase, with the 95% confidence interval placing the increase between 10% and 28%.

Trade-offs

The lifetime risk for bowel cancer in Britain is about 61 cases for every 1,000 people. Split by gender, the lifetime risk for bowel cancer is around 72 cases for every 1,000 men and 54 cases per 1,000 women. Cancer Research UK states there are 56 cases of bowel cancer during the lives of every 1,000 low meat-eaters. This means, assuming the 2011 analysis is correct, the heightened risk among high consumers of processed meats should imply around 66 incidences of bowel cancer in this group.

151026-IARC-Meat-rating-UPDATE2

Cancer Research UK draws attention to these categories. (Source: Cancer Research UK)

Life is about trade-offs, between different foods, different hobbies and different joys. Research of this kind merely highlights what trade-offs are to be made. There are those who will respond to this news by eating copious amounts of bacon.

References

[1] IARC, 2015. IARC Monographs evaluate consumption of red meat and processed meat. Available from: https://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf [Accessed: 22nd November 2015]

[2] Genower, E., 2015. Bacon And Sausages As Big A Cancer Threat As Cigarettes, Say World Health Organisation. Yahoo! News. Available from: https://uk.news.yahoo.com/bacon-sausages-big-cancer-threat-083910518.html#qRZkabH [Accessed: 22nd November 2015]

[3] IARC, 2015. Agents classified by the IARC Monographs, Volumes 1-114. Available from: http://monographs.iarc.fr/ENG/Classification/ [Accessed: 22nd November 2015]

[4] Dunlop, C., 2015. Processed meat and cancer — what you need to know. Cancer Research UK. Available from: http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/ [Accessed: 22nd November 2015]

[5] Chan, D. S. M., Lau, R., Aune, D., Vieira, R., Greenwood, D. C., Kampman, E., and Norat, T., 2011. Red and Processed Meat and Colorectal Cancer Incidence: Meta-Analysis of Prospective Studies. PLoS One. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3108955/ [Accessed: 22nd November 2015]

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This entry was posted on November 22, 2015 by in National Politics and tagged , .
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