Since 2015, when the World Health Organization (WHO) classified processed meats as Group 1 carcinogens, science has supported the idea that these foods pose a serious threat to our bodies. New research from a branch of the WHO called The International Agency for Research on Cancer (IARC) aims to adjust this classification by clarifying that processed meats that contain nitrites are the worst carcinogenic offenders.
The study, which comes from scientists at the Institute of Global Food Security at Queen's University Belfast (QUB) in the United Kingdom, was published recently in Nutrients. It details the researchers’ findings from analyses of previous studies linking processed meat consumption and cancers of the colon, rectum, and bowel.
But back up for a second – what do we mean when we talk about processed meats? According to IARC, this category includes meat that has been cured, salted, smoked, fermented, or preserved in some way, such as frankfurters, bacon, ham, sausages, corned beef, beef jerky, and canned meat. During certain curing or flavoring processes, sodium nitrite is used to aid in the procedures, and as we know, sodium nitrites are known to be dangerously carcinogenic.
Back to the study. According to the researchers’ analyses, while roughly half the previous studies asserted evidence of a link between processed meat consumption and colorectal cancer, breaking down the categories of processed meats into those containing nitrites and those not containing nitrites, they found a significant difference. Compared to approximately 50% for processed meat, they saw a 65% link for colorectal cancer with processed meats that contained nitrites.
"When we looked at nitrite-containing processed meat in isolation, which is the first time this has been done in a comprehensive study, the results were much clearer," says first study author William Crowe, Ph.D., of the School of Biological Sciences at QUB, "Almost two-thirds of studies found a link with cancer.”
Although the researchers urge that more investigation will be needed in order to fully draw conclusions that could be implemented as suggestions regarding healthy diets, they say that sticking to nitrite-free processes meats is the best option we have at the moment.
"There are so many variables when it comes to people's diets," comments senior study author Brian D. Green, Ph.D., from QUB's School of Biological Sciences. "But based on our study, which we believe provides the most thorough review of the evidence on nitrites to date, what we can confidently say is that a strong link exists between nitrite-containing processed meat, such as frankfurters, and [colorectal cancer]."