Processed meats cause colorectal cancer
Cold cuts platters at parties and quick bites on the go are so convenient choices! But how high taxes you have to pay for that convenience? Let’s take a closer look.
Meat which has been modified in order either to improve its taste or extend its shelf life by salting, curing, fermentation, smoking or other methods is called processed meat. The list of processed meats is long, just to mention a few: bacon, ham, hotdogs, sausages, salami, corned beef, beef jerky, canned meat and meat-based sauces.
Processed meats in our diet
According to the report titled “Processed Meats in the United States”, on average, Americans consume processed meats 50.7 times per year as a main dish (59.8%) or a side dish (30%), and occasionally as a snack (5%). Of those who eat processed meats, 64.1% will consume these products an average of three times in a two-week period. Children between 6-12 years of age have the highest consumption rates, followed by adult males aged 65 years and older.
The International Agency for Research on Cancer (IARC) at the World Health Organization classifies processed meat as a Group 1, carcinogenic to humans, since it has found sufficient evidence that consumption of processed meat by humans causes colorectal cancer.
An increased intake of red and processed meat appears to increase the risk of death from cancer, heart disease and other diseases.
Why processed meat causes colorectal cancer
The reasons why processed meat increases the risk of colorectal cancer have been under intense investigations. Some possibilities include:
- Cooking temperature: High temperature (such as deep pan frying or grilling directly over an open flame) plays a crucial role in forming carcinogens. Cooking meat until very well done produces heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH), which have been found to be mutagenic – they cause changes in DNA that may increase the risk of cancer. HCA is not found in significant amounts in foods other than meat cooked at high temperature, whereas PAH can be found in other charred foods, as well as in cigarette smoke and car exhaust fumes.
- Chemicals that are formed when the meat is digested or processed: Just think – what colour meats have when you cook them in your kitchen. Have you ever seen red meat after boiling or cooking it in an oven? So, to keep processed meat looking nice on the shelves and to preserve it nitrates are added. Nitrates are converted to nitrites in the stomach. Nitrites contribute to the formation of cancer-causing N-nitroso compounds.
- Dietary heme iron: Red meat contains higher amounts of heme iron than white meat. Heme iron has been shown to cause damage to the mucosa of the colon and promoted increased cell growth in animal studies. It also promotes the formation of cancer-causing N-nitroso compounds.
IARC Monograph evaluates consumption of red meat and processed meat
In October, 2015, 22 experts from 10 countries met at the International Agency for Research on Cancer (IARC) in France to evaluate the carcinogenicity of the consumption of red meat and processed meat. The IARC Working Group evaluated more than 800 different studies on cancer in humans (some studies provided data on both types of meat; in total more than 700 epidemiological studies provided data on red meat and more than 400 epidemiological studies provided data on processed meat). These assessments were published in volume 114 of the IARC Monographs.
Here are major highlights:
- According to the most recent estimates by the Global Burden of Disease Project, an independent academic research organization, about 34,000 cancer deaths per year worldwide are attributable to diets high in processed meat. These numbers contrast with about 1 million cancer deaths per year globally due to tobacco smoking, 600,000 per year due to alcohol consumption, and more than 200,000 per year due to air pollution.
- The scientists concluded that each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%.
- The risk of colorectal cancer could increase by 17% for every 100 gram portion of red meat eaten daily.
- People who ate more than 160g of processed meat each day – versus less than 20 grams – were 44% more likely to die early, in particular from cardiovascular disease but also from cancer (160g of processed meat is equivalent to two large Italian sausages or three slices of deli ham and three small hot dogs).
Smoked meat and fish
Curing and smoking have been used for thousands of years to preserve foods like meat and fish. Smoking exposes meat or fish to the smoke of a wood or charcoal fire. The foods absorb large amounts of the tar that comes off the smoke. These tars contain cancer-causing compounds. In Canada, vitamin C may be added to some preserved meats. Vitamin C keeps nitrites from changing into nitrosamines, which may help reduce the risk of cancer associated with these chemicals.
Too much salt
Processed meats like bacon, salami, hot dogs and bologna are often high in fat and salt. There is overwhelming evidence that eating these types of foods greatly increases the risk of colorectal and stomach cancer. Many studies suggest that the rates of stomach cancer are much greater in Japan where a traditional diet contains many foods that are highly salted, and/or smoked.
Reducing your risk
So, should you stop eating mouthwatering cold cuts? No, not completely. Indulge yourself once in a while. Here are some other tips:
- Better save a meat platter for a party or for other special occasions.
- Enjoy your hot dog at a baseball game.
- Make a pizza without pepperoni, or bacon, or ham – use boiled chicken chunks with lots of veggies and herbs instead.
- Do not add salt to processed meats – they have more than enough.
- Eat salt-preserved foods in small amounts and not often.
Attention meat lovers! The effects of cold cuts on your health depend on which ones you choose and how much you eat. The more you eat, the greater the risk. Moderate the consumption of red meat and processed meat. Many dietary guidelines also recommend limiting processed meat intakes, but these are focused mainly on reducing of fat and sodium, which are risk factors for cardiovascular disease and obesity.