If your diet is rich in processed meat, you may want to reconsider. Although studies sometimes have different estimates of how bad processed meat is for you, there is a definite link between this type of meat and some forms of cancer.
A growing problem
The link between meat consumption and our health is complex, but processed meat, in particular, has been linked to a number of health problems.
Processed meat refers to any meat that has been transformed through processes like salting, curing, smoking, or any other form of processing, whether it's to improve its flavor or for preservation. Most processed meat is red meat (either pork or beef), but can be made from other types of meat or meat by-products, including blood.
In North America, around 70% of people consume red or processed meat on any given day, with red meat consumption being slowly on the decline, but processed meat consumption being on the rise. In developing nations, processed meat consumption is generally lower, but also rising. Europe stands as an exception, with the consumption of processed meat being on the decline.
Clear figures are hard to find, because the definition of processed meat is so wide. Overall, though, the world seems to have quite an appetite for processed meat -- and it's a problem.
What the science says
The World Health Organization classifies processed meat as a Group 1 carcinogenic substance, a category that includes things like alcohol, tobacco, ionizing radiation, as well as several pathogens. This classification is mostly based on a report by the International Agency for Research on Cancer (IARC), a group of international experts that scrutinize large volumes of evidence on cancer research.
In this particular case, the IARC report is based on over 800 studies -- it's as close to scientific consensus as you can get on this issue.
Some individual or small scale studies may yield different results (either due to smaller sample size, other confounding factors, or less meticulous methodology), but when you look at the big picture, at all the relevant studies on the matter, processed meat is definitely carcinogenic.
"According to our own findings and from reviewing other quality literature, red/processed meat has a strong risk for carcinogenesis especially in the bowel," explains Vinod Gopalan, a Senior Lecturer in Histopathology at Griffith University. Gopalan joined other experts on Metafact, a platform that attempts to assess scientific consensus on different topics .
"Our own studies have indicated that controlled dose dependent exposure of some of the chemical molecules from red/processed meat consumption increases normal bowel cell proliferation and activation of many cancer causing genes. This is in alignment with previous experimental studies. "
Other quoted experts expressed similar views. While one sausage won't kill you, the link between processed meat and some types of cancer is undeniable.
How big is the risk
According to the IARC report, those who ate the most processed meat had around a 17% higher risk of developing bowel cancer (compared to those who ate the least). It's not just just bowel cancer, either. A study of some 500,000 people published in 2019 found that the risk of colorectal cancer rises by 19% for every daily 25-gram serving. In other words, one slice of ham a day raises your relative risk of colorectal cancer by 19%.
It's important to keep in mind that this is relative risk. A person has an average risk of around 5% over their entire lifetime (though this varies greatly based on a number of factors), so we're talking about a 19% increase of this 5% -- as in, a 1% overall increase.
Another way of looking at it, according to this study carried out in the UK, is that 1.5% of cancers are caused directly by processed meat. At the population level, this is a significant number -- but whether it's enough to change personal options... that's a different problem.
Tim Crowe, a nutrition expert quoted by Metafact, comments:
"Even the highest-level committee members of the IARC were not saying that if you eat a sausage you are a candidate for cancer. What they were warning about was that if processed meats were a daily feature of your diet, your risk of bowel cancer would go up."
"There are multiple factors which should be considered here. For example, hereditary predisposition, salting, other chemical additions during meat processing, fat/oil, alcohol, amount meat consumption and the use of vegetables during this consumption," Gopalan adds.
More recent research also recommends cutting down on processed meat, especially if you're a regular consumer. According to a meta-analysis (a study of studies), diets low in processed meat are associated with:
- 13% lower risk of premature death;
- 14% reduction in cardiovascular mortality;
- 14% reduction in non-fatal stroke;
- 24% reduction in type 2 diabetes;
- 10% reduction in overall cancer incidence;
- 11% reduction in cancer mortality.
All these findings are statistically significant and are unlikely to be owed to chance.
However, data is more abundant in wealthier countries, and scarcer in less developed countries, which makes it hard to draw wide conclusions. However, according to some peer-reviewed estimates, some 4.4% of all global deaths worldwide are directly associated with red or processed meat. This link is strong enough that some researchers are debating taxing processed meat as a carcinogen due to its negative impact -- much like tobacco is taxed. This type of call is still controversial, but the connection between processed meat and some types of cancer is undeniable. There's still a very important debate about just how bad it is, and whether it's optimal to reduce or eliminate processed meat, but the consensus suggests that the link does exist.
The regular consumption of processed meat will likely increase your risk of cancer. Of course, one slice of ham or bacon won't kill you (neither will one cigarette), but there is a growing body of evidence suggesting that the more processed meat you eat, the more your risk increases.
Eating less processed meat can make a difference, especially if it's coupled with a healthy diet and an active lifestyle.