"There is much confusion about what “processed meat” actually means, a confusion encouraged by the bacon industry, which benefits from us thinking there is no difference between a freshly minced lamb kofta and a pizza smothered in nitrate-cured pepperoni. Technically, processed meat means pork or beef that has been salted and cured, with or without smoking. A fresh pound of beef mince isn’t processed. A hard stick of cured salami is.
The health risk of bacon is largely to do with two food additives: potassium nitrate (also known as saltpetre) and sodium nitrite. It is these that give salamis, bacons and cooked hams their alluring pink colour. Saltpetre – sometimes called sal prunella – has been used in some recipes for salted meats since ancient times. As Jane Grigson explains in Charcuterie and French Pork Cookery, saltpetre was traditionally used when brining hams to give them “an attractive rosy appearance when otherwise it would be a murky greyish brown”.
In earlier centuries, bacon-makers who used saltpetre did not understand that it converts to nitrite as the meat cures. It is this nitrite that allows the bacteria responsible for cured flavour to emerge quicker, by inhibiting the growth of other bacteria. But in the early 20th century, the meat industry found that the production of cured meats could be streamlined by adding sodium nitrite to the pork in pure form. In trade journals of the 1960s, the firms who sold nitrite powders to ham-makers spoke quite openly about how the main advantage was to increase profit margins by speeding up production. One French brand of sodium nitrite from the 60s was called Vitorose or “quick-pink”.
Nitro-chemicals have been less of a boon to consumers. In and of themselves, these chemicals are not carcinogenic. After all, nitrate is naturally present in many green vegetables, including celery and spinach, something that bacon manufacturers often jubilantly point out. As one British bacon-maker told me, “There’s nitrate in lettuce and no one is telling us not to eat that!”
But something different happens when nitrates are used in meat processing. When nitrates interact with certain components in red meat (haem iron, amines and amides), they form N-nitroso compounds, which cause cancer. The best known of these compounds is nitrosamine. This, as Guillaume Coudray explained to me in an email, is known to be “carcinogenic even at a very low dose”. Any time someone eats bacon, ham or other processed meat, their gut receives a dose of nitrosamines, which damage the cells in the lining of the bowel, and can lead to cancer." Bee Wilson (2018) https://www.theguardian.com/news/2018/mar/01/bacon-cancer-processed-meats-nitrates-nitrites-sausages
