Dietary intake of nitrite-containing frankfurter exacerbates colorectal cancer in mice, new study finds

A group of researchers from Queens University have recently published a paper demonstrating that nitrite-containing sausages can exacerbate the development of colorectal cancer (CRC) pathology in mice, and this is associated with increased lipid peroxidation, metabolic alternation wide-ranging and intestinal dysbiosis.    

CRC is among the most common cancer (second in Europe and third worldwide). It can be hereditary, but its occurrence can also be linked to environmental factors and diet. A diet high in processed meat, including meats with salt preservatives such as sodium nitrite, is suggested as a major risk factor for developing CRC.    

The International Agency for Research on Cancer (IARC) advises avoiding the consumption of processed meat (e.g. frankfurters, ham, sausages, and canned meat) as these type of products are classified as a group 1 carcinogen (carcinogenic to humans). Processed meat is often treated with nitrite to prevent the growth of Clostridium botulinum and to enhance the appetibility of the product (contributing to its typical color and taste). Ingested nitrite has the potential to form N-nitroso compounds (NOCs), including nitrosamines, some of which are known to be carcinogenic. Recent studies have shown that NOCs are involved in the etiology of various types of cancer, in particular those of the gastrointestinal tract.    

This study examined how the CRC pathology and metabolic status of mice with multiple intestinal neoplasia of adenomatous polyposis coli were perturbed after 8 weeks of pork consumption.    

The researchers found that a modest inclusion of pork sausage containing sodium nitrite in the mice's diet significantly increased the number of intestinal tumors present. A similar inclusion of nitrite-free pork sausage or ground pork did not increase the number of cancers. Frankfurter consumption was also associated with higher levels of oxidative stress than any other dietary group. The authors point out that all dietary interventions in this study affected the composition of the fecal microbiota to some extent. However, the reduced microbial diversity of the frankfurter group suggested that this diet caused intestinal dysbiosis.    

The researchers highlight the advantages of their study compared to previous work in this area:  
- the cancer was induced spontaneously and not chemically;  
- the quantities of processed meat used are more realistic (all previous studies provided a minimum of 50% of processed meat in the diet while this study found a measurable effect with only 15%);  
- other relatively unexplored mechanisms, through which diet affects CRC, have been considered (e.g. metabolome and microbiome).