Researchers have suspected for a long time that diets may be linked to the risk of cancer. As research progressed to find the link between cancer and diet, scientists started noticing that people who were on a plant-based diet had a lower risk of developing cancer compared to people who consumed meat. Currently, there is enough scientific evidence to prove that the risk of colon cancer is higher in people who eat more of processed meat and red meat, and the proofs also suggest that stomach cancer is strongly linked to consumption of processed meat.

In an October 2016 report of the World Health Organization, the body stated that processed meats such as bacon and sausage cause cancer, and that the probability of red meat including beef and lamb causing cancer is very high.

Also, the International Agency for Research on Cancer carried out an extensive review of available research on things that cause cancer. In their report, the body classified processed meat as a definite cause of cancer and stated that red meat has a high probability of causing cancer.

Red meat includes meat that has a red color before it is cooked and includes beef, lamb, and pork. Processed meat is any meat that has been cooked cured, smoked or salted and includes products such as bacon, hot dogs, sausages, salami, and ham.

Of all the cancers linked to meat consumption, the one with the most evidence is colon cancer. To cite an example, the World Cancer Research Fund analyzed past studies on the relationship between meat and colon cancer. The researchers at the WCRF divided the data into categories of people who consumed a high amount of processed meat and red meat and those who ate less. In the results of the final analysis, researchers found that both processed meat and red meat could cause cancer, but processed meat increased the risk higher than red meat. According to the results, people who eat the highest amount of processed meat had about 17 percent higher chance of coming down with colon cancer.