Cooked ham was classified by the WHO as a type 1 carcinogen in 2015: why is it being talked about again, and what does it mean exactly?
The news seems to be one of those made specifically to ruin the lunch break, or on the contrary to motivate the Veganuary: cooked ham, the main filling for toast and sandwiches, has been classified as a type 1 carcinogen by the World Health Organization. This is reiterated by viral videos circulating on the Internet, commented on by nutritionists and covered by the news. Is there anything to worry about? What has changed, and why is the topic at the center of attention again?
Ham is carcinogenic. We’ve known this for over 10 years
Cooked ham has actually been included by the International Agency for Research on Cancer (IARC), a body of the World Health Organization, in the list of certain carcinogens (the so-called group 1). However, it didn’t happen in the last few days, but in October 2015: we reported it here.
The IARC considers type 1 carcinogens to be substances for which there is strong evidence of carcinogenicity, therefore those for which there is sufficient evidence to demonstrate their relationship with the risk of developing tumors. However, IARC does not specify the dosages or exposure times needed for each of the substances on this list to actually cause cancer.
In that October 2015, not only cooked ham ended up in the group of type 1 carcinogens, but the entire family of processed meats, such as salami, mortadella, raw ham, breasola, speck, frankfurters, sausages, canned meats. The decision was made on the basis of a review of over 800 scientific articles conducted by 22 experts, which confirmed an association between the consumption of processed meats and certain types of cancer, especially tumors affecting the intestine and digestive system: colorectal, pancreatic and stomach cancer. However, a positive association with prostate cancer was also found.
Should we then stop eating cooked ham (and other cured meats)?
It’s not that if you ate cooked ham for lunch then you should be alarmed. We need to think in terms of probability: foods considered type 1 carcinogens, such as processed meats, increase the probability of getting cancer, so the less you eat, the less likely this is to happen, even more so if, in addition to moderation in the consumption of cured meats, you adopt a healthy lifestyle (no smoking, little alcohol, lots of physical activity…). In the study that inspired the WHO decision, it was concluded that every daily portion of 50 grams of cured meats eaten increases the risk of colorectal cancer by 18%. Nutritional guidelines recommend not exceeding this dose in a week.
Why are processed meats carcinogenic?
The substances used in the processing of processed meat could favor the formation of carcinogenic substances.
Nitrates and nitrites, preservatives that keep processed meat edible for longer and give it flavor and colour, can undergo chemical alterations in our intestines that transform them into nitrosamines, molecules that can damage the wall of our intestine and encourage the proliferation of tumor cells. It could be precisely the nitrates that make processed meat more dangerous, due to the risk of tumors, compared to unprocessed red meat (which in any case is among the substances probably carcinogenic to humans, group 2A).
Heme iron, a chemical complex that makes up hemoglobin, present in foods of animal origin and easily absorbed by the intestine, can also promote the transformation of nitrites into nitrosamines. Not to mention that processed meats are rich in salt and saturated fats, elements which are however associated with a greater risk of cardiovascular and oncological problems, and that a high consumption of cooked ham and other cured meats can reduce that of healthier foods, such as vegetables.
Even if the oncogenic risk posed by each individual food on the careful list, such as cooked ham, is small, the WHO considers it important to warn against excessive consumption because these foods are very widespread, because they are appetizing and immediately ready, and because more and more people consume them even in medium-low income countries.
But is it true that eating cooked ham is like smoking?
No. In the group of certain carcinogens there are also asbestos, ethyl alcohol and smoking, ultraviolet radiation and the Papilloma virus, because there is indeed certain evidence that these substances promote cancer. But just because they belong to the same list doesn’t mean they have the same power to promote cancer: smoking and alcohol are much more potent carcinogens than processed meats.
So why is there a return to talking about cooked ham?
No one has figured it out for sure, but one reason may be the publication of two studies on the harmful impacts of food preservatives on human health: preservatives that are present in processed meats. According to research, which we wrote about a few days ago (to learn more), massive consumption of food additives is linked to a higher risk of cancer and type 2 diabetes.
