The consumption of processed meat containing nitrites is associated with an increased risk for colorectal cancer (CRC), according to a literature review published in Nutrients.
For more than a decade, there has been concern around the correlation between processed meat consumption and CRC risk. Sodium nitrite, a preservative and flavor enhancer added to many processed meats, has been isolated as a probable contributor to this risk. To assess this relationship, investigators reviewed articles from PubMed, Scopus, and Web of Science. Of 17 human studies specifically investigating processed meat containing nitrites, 5 found the consumption of meat containing nitrites to have no effect on CRC risk, and 1 study reported that nitrite-containing meat was protective against CRC risk. The rest of the studies, a total of 11, found an increased risk for CRC from the consumption of nitrite-containing processed meat. It has been proposed that the mechanism underlying this elevated risk involves the formation of N-nitroso compounds after the consumption of processed meat containing nitrites.
The investigators acknowledge that the majority of human studies involved in the review did not take into account additional risk factors such as consumption of fats and fiber, smoking, and physical activity. Nitrites and CRC risk also have a much less established relationship than other known carcinogens such as smoking. Human studies supporting the nitrite-CRC risk hypothesis had some methodological limitations as well. In conclusion, the investigators state that their findings support concerns about nitrite usage, but that additional well-designed research is needed to further confirm the findings.
Crowe W, Elliott CT, Green BD. A review of the in vivo evidence investigating the role of nitrite exposure from processed meat consumption in the development of colorectal cancer. Nutrients 2019;11(11):2673.