Yes, experimental and epidemiological studies show that the consumption of red meat (beef, pork, lamb, and horse) and processed meat convincingly increases the risk of colorectal cancer (CRC).
Processed meat means red meat preserved by smoking, curing, salting or by adding preservatives. There are many types of processed meats such as ham, bacon, pastrami, salami, sausages, hot dogs, etc. Furthermore, one intake of red meat per week increases the risk of CRC by about 40%, and each 50 g of processed meat increases the risk by about 20%.
Cancer-associated chemicals can be formed in red and processed meats, depending on the cooking method and doneness level (rare, medium rare etc). The first is polycyclic aromatic hydrocarbons (PAHs). PAHs are a group of organic compounds that can also be found in cigarette smoke and coal. PAHs has been linked to causing DNA damage. If the DNA damage is not repaired correctly, mutations arise and can result in CRC.
Besides that, heterocyclic aromatic amines (HCAs) are found in abundance in red and processed meats. They can induce mutations in our DNA and increase the risk of CRC.
Lastly, the presence of nitrates and nitrites in processed meat had been associated with CRC. Nitrates and nitrites react with other chemicals in our body to modify the structure of our DNA and this can result in CRC.
However, do note that many of these studies were conducted using animal models whereby the animals were fed with a high amount of cancer-associated chemicals. The threshold dosage that causes CRC in animal models can be very different from that of humans.
Although the consumption of red and processed meats is highly correlated to increased CRC risk, the mechanism of how the active ingredients contribute to cancer is still under investigation.