Many questions have remained unanswered in a long-standing debate over the cancer risk attributable to eating meat. For instance: Does the risk apply to red as well as processed meats? Are all types of processed meat a potential hazard? How much needs to be eaten to impart a significant risk? What is responsible for the increased risk?

The researchers noted that colorectal cancer (CRC) is the third most prevalent malignancy worldwide and the second most prevalent in Europe. Around 5% of cases are attributable to familial adenomatous polyposis, but the rest are believed to be influenced by environmental factors. Diet is “a leading candidate in the search for causes of CRC”, and “an important modifiable risk factor,” they said.

Public Health Advice at Odds With Reality

“Current public health advice treats all processed meat equally when in reality there are many differences in their composition,” said the researchers. “Most notably, there is the addition of sodium nitrite as a preservative, which is present in some products and not in others.” For example, nitrites are not traditionally an ingredient in the manufacture of British/Irish sausages but are more common in continental European sausages.

While sodium nitrite uniquely prevents the growth of Clostridium Botulinum and contributes to the color and taste of processed meat, ingested nitrite has the potential to form N-Nitroso compounds (NOC) including nitrosamines, some of which are known to be carcinogenic. NOCs have been proposed to be involved in the etiology of several types of cancer, particularly those in the gastrointestinal tract.