The American Institute for Cancer Research links red and processed meat to a higher risk of colorectal cancer according to a new report.

During a five-year review of more than 7,000 studies, researchers looked at 87 studies on the potential link between colorectal cancer and red meat, including beef, pork, and lamb. The group recommends limiting consumption of red meat to 18 ounces per week. The evidence against processed meat such as bacon, ham, sausage and lunchmeat is even stronger and the researchers could find no level at which consumption of these products is safe. They suggest eating these products sparingly.

Red meat may be linked to a higher risk of cancer through several mechanisms. First, grilling meat produces cancer-causing chemicals. The fat in red meat also stimulates the forming of substances which can damage the DNA in the colon. And the iron in red meat can generate cancer-causing substances as well as free radicals, which can damage DNA.