In October 2015, 22 scientists from 10 countries met at IARC to review current evidence linking red and processed meat with risk of bowel and other cancers.
Red meat includes pork, veal, lamb, mutton, beef, horse and goat, including minced and frozen meat. Processed meat includes meats preserved by smoking, curing, fermentation or salting, or by adding chemical preservatives to extend its shelf life or change its taste. Inconsistent definitions of processed meat are used in the scientific literature but this usually includes bacon, ham and salami.
According to a summary published in Lancet Oncology (http://dx.doi.org/10.1016/), this expert committee, which based its findings on the relationship between meat and colorectal cancer risk, classified consumption of processed meat as ‘carcinogenic to humans’ and consumption of red meat as ‘probably carcinogenic to humans’ as evidence is limited. These conclusions are largely based on the findings of cohort studies investigating the risk of colorectal cancers in high vs low consumers of red and processed meat, along with some case-control studies and supporting mechanistic evidence. For processed meat, positive associations were reported in 12 of 18 cohort studies but only half of the 14 cohort studies looking at red meat. Media reports suggesting that meat is now considered a major carcinogen, however, alongside smoking and alcohol, are highly misleading as the effect is dose-related and relatively small.
A positive association with the consumption of processed meat was also found for stomach cancer and consumption of red meat was positively associated with pancreatic and prostate cancer, although detailed evidence on which this was based has not yet been provided.
In the UK, the Scientific Advisory Committee on Nutrition reviewed the evidence linking diet and cancer in 2010. Current advice is to limit consumption of processed meat and to keep your consumption of red meat to 500g of cooked meat a week or less (70g per day). This is also supported by the World Cancer Research Fund (WCRF). To put this into context, a medium portion of roast beef or pork is about 90g and a medium steak is about 145g (cooked weight). Average intake in the UK is around this level (71g/day) but those with higher meat intake should consider cutting down.
Red meat is a good source of protein, iron and zinc and those wanting to avoid meat need to ensure that other foods containing these nutrients are included in the diet. It is also important to consider other lifestyle changes which have been shown to be strongly linked to reduced risk of cancer such as losing weight, stopping smoking, taking more exercise and reducing alcohol consumption.