There has been a lot of misinformation and confusing coverage around the release of the World Health Organization (WHO)’s findings linking processed and red meat to cancer. The science isn’t new but the vastness of the research collected by such an influential organization has led to a subsequent media frenzy. As a result, most people don’t really know where they stand, or whether they should take red meat off their shopping list altogether.
Is red meat linked to cancer? The short answer is, yes, processed red meat is, but scientifically, we don’t know for sure about natural red meat yet. However, experts certainly believe it is, and there’s a good reason for that…
Processed meat and red meat were high priorities when an international advisory committee met in 2014. The committee recommended an evaluation by the International Agency for Research on Cancer (IARC) Monographs Program. That recommendation was based on studies of epidemics that suggested small increases in the risk of cancer may be associated with high consumption of red meat and processed meat.
This news isn’t actually new. It has been brewing and trickling out in individual studies for years now, and it has been widely accepted for a long time that meat can increase the risk of bowel cancer. This collaboration of research, however, is significant because it comes from the IARC. Their findings carry weight, and are listened to by governments and regulators. The working group considered more than 800 studies that investigated associations of more than a dozen types of cancer with the consumption of red meat or processed meat in many countries and populations with diverse diets. The most influential evidence came from large studies conducted over the past 20 years.
This is the area that has become very clouded, with the industry trying to protect its reputation and journalists trying to squeeze the most juicy bits of the report into brief news bulletins and articles. What the researchers have found, after thoroughly reviewing an accumulation of scientific literature that had been mounting in recent years, is that the consumption of red meat is “probably” carcinogenic to humans, based on limited evidence that the consumption of red meat causes cancer in humans, and strong mechanistic evidence supporting a carcinogenic effect. The association is mainly relevant to colorectal cancer, but there are also links to pancreatic cancer and prostate cancer.
Processed meat, on the other hand, is classified as conclusively carcinogenic to humans, based on sufficient evidence that the consumption of processed meat causes colorectal cancer. The group of 22 experts from 10 different countries who worked on the report also found an association with stomach cancer, but that evidence was not conclusive.
To put it statistically, the experts have concluded that each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%.
Researchers haven’t conclusively found exactly how processed meat, and possibly red meat, cause cells to become cancerous. The findings so far blame chemicals that are found in the meat, starting with heme, which is part of the red pigment in the blood. Heme is broken down in the gut to form N-nitroso compounds that can damage cells in the bowel lining. As a result of this, other cells in the bowel lining are forced to replicate in order to heal, and that replication can increase the risk of problems with the development of the extra cells’ DNA. That is the first stage in a sequence of events that can lead to cancer.
“For an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed,” Head of the IARC Monographs Programme Dr Kurt Straif said. “In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance.”
The research also found that high-temperature cooking methods generate compounds that may contribute to carcinogenic risk, such as direct contact with a flame or hot surface. The suggestion is that hot barbecues or frying pans can cause an increased production of certain carcinogenic chemicals like polycyclic aromatic hydrocarbons and heterocyclic aromatic amines. However, there was not enough data available for the IARC Working Group to reach a solid conclusion on this theory yet. This is another area that is confusing consumers because the industry is understandably publicizing the lack of scientific evidence that currently exists, but scientists are saying, it is a risk, and it might very well be proven in the long-run.
Director of the IARC, Dr Christopher Wild, said the findings further support current public health recommendations to limit our intake of meat. “At the same time, red meat has nutritional value. Therefore, these results are important in enabling governments and international regulatory agencies to conduct risk assessments, in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations.”
Smoking Versus Eating Red Meat
This is an interesting link that has been drawn during the aftermath of the research findings being released. Processed meat has now been classified as carcinogenic to humans (Group 1), which puts it in the same category as tobacco smoking and asbestos, which are also both classified as carcinogenic to humans (Group 1). Red meat, on the other hand, is considered potentially carcinogenic to humans (Group 2A). While processed meat has been placed in the same category as tobacco and asbestos, it does not mean it is as dangerous as them. The classification is based on the strength of scientific evidence, not the level of risk. To put it into perspective; smoking three cigarettes per day increases the risk of lung cancer by 600%, while eating 50 grams of processed meat per day increases the risk of colorectal cancer by 18%.
The most interesting thing, however, is how similar it is to the discussion on smoking several decades ago. Like the processed and red meat industries, tobacco stood to lose a lot when science was in its early stages of linking smoking to cancer, and the uproar from consumers was also very similar. That’s not to say the science of red and processed meat will necessarily go the same way, but studies are in their very early stages, and there is still a lot to be revealed, proven and disproven, such as the link with high-temperature cooking.
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