Indeed, meat preservation using methods such as salt-curing, smoking, drying, fermenting or any combination of these has been in recorded history since at least 1500 BCE. Meat is a valuable protein source and with no mechanical refrigeration meant our ancestors out of necessity had little choice but to develop ways to preserve meat. For people in reasonably developed countries, food supply chains are reasonably robust in supplying fresh or minimally processed produce safely and reliably. Most of us consume processed meats for culinary delight and convenience. The curing process has lost its relevance to prevent our households from going hungry between harvests or dying from microbially contaminated meat. While curing does prevent food-borne diseases like botulinum currently, with what the risks we know about and the alternatives we have, eating processed meat does seem unnecessarily risky.
Processed meats are bad because they are rich in the haem molecule, found in myoglobin, red blood cells and in cytochrome, an iron-containing protein in cells. When meat is digested, it produces a soup of amino acids (nitrogen-based molecules), the breakdown products of haem and fats. Haem’s breakdown products alone are toxic to our gut cells and are known to be carcinogenic. These very same products also have strong oxidative potential and cause a fat oxidation chain reaction which creates free radicals thus increasing oxidative stress on gut cells which also leads to cellular and DNA damage and are cancer-inducing. To add salt to the wound, some of the haem breakdown products also react with broken amino acid chains to form N-nitroso compounds. These compounds are known carcinogens and are particularly damaging to the cells in the bowel lining. And this is actually just for red meat alone! We haven’t introduced the negative impacts of nitrites used to make the meat deliciously pink and tasty!
Nitrites such as sodium or potassium nitrite are added as preservatives in many cured meats. These increase the production of N-nitroso compounds in the gut and, yup, you guessed it, reacts nicely with haem’s breakdown products to pump out even more of these carcinogenic molecules. Finally, processes like smoking or charring meats over high temperatures (roasting, charcoal or grilling) produces a broad class of compounds called polyaromatic cyclic hydrocarbons (PAH). They form through complex chemical reactions mediated by heat and smoke. PAHs are known carcinogens but we don’t know exactly how they affect cancer risk in individuals.
But hold on, beetroot and many vegetables are rich in nitrogen compounds and nitrates. Nitrates have a different oxidation state (note the ‘A’ instead of the ‘I’ in nitrate). Not only do vegetables lack heam and the fats, the nitrates are chemically different and actually reduce certain cancer risks and cardiovascular risks.