Meat processing began as soon as people realized that cooking and salting prolongs the life of fresh meat. It is not known when this took place; however, the process of salting and
sun-drying was recorded in Ancient Egypt, while using ice and snow is credited to early Romans, and
canning was developed by
Nicolas Appert who in 1810 received a prize for his invention from the French government.[3] Medical health organizations advise people to limit processed meat consumption as it increases risk of
colorectal cancer.[4][5][6][7]
Preservatives
Nitrate and
sodium nitrite found in processed meats can be converted by the human body into
nitrosamines that can be carcinogenic, causing mutation in the colorectal cell line, thereby causing
tumorigenesis and eventually leading to cancer.[8] Processed meat is more carcinogenic compared to unprocessed red meat because of the abundance of potent nitrosyl-heme molecules that form
N-nitroso compounds.[9]
A principal concern about sodium nitrite is
Nitrosation/
nitrosylation, the formation of carcinogenic
nitroso-compounds in meats containing sodium nitrite or potassium nitrate,[10] especially
nitrosyl-haem (
nitrosyl heme).[11] In addition to nitrosyl-haem, carcinogenic
nitrosamines can be formed from the reaction of
nitrite with secondary
amines under acidic conditions (such as occurs in the human stomach) as well as during the curing process used to preserve meats.[citation needed]
Nitrate and nitrite are consumed from plant foods as well as animal foods, with 80% of a typical person's nitrate consumption coming from vegetables, especially
leafy and
root vegetables such as
spinach and
beets.[12] Some nitrate is converted to nitrite in the human body.[12] Nitrate and nitrite are classified as
generally recognized as safe (GRAS) by the
U.S. Food and Drug Administration, and are not directly carcinogenic. Yet, when nitrate or nitrite interact with certain components in meat, such as heme iron, amines, and amides, they can form
nitroso compounds, which may contribute to the association between consumption of processed meats and higher incidence of colorectal cancer.[13]
In 2020, the
American Cancer Society stated that "it is not known if there is a safe level of consumption for either red or processed meats. In the absence of such knowledge, while recognizing that the amount of increased risk isn't certain, the ACS recommends choosing protein foods such as fish, poultry, and beans more often than red meat, and for people who eat processed meat products to do so sparingly, if at all."[4]
^Jeyakumar A, Dissabandara L, Gopalan V (April 2017). "A critical overview on the biological and molecular features of red and processed meat in colorectal carcinogenesis". Journal of Gastroenterology. 52 (4): 407–418.
doi:
10.1007/s00535-016-1294-x.
PMID27913919.
S2CID20865644.
^Lijinsky, William (July 1999). "N-Nitroso compounds in the diet". Mutation Research/Genetic Toxicology and Environmental Mutagenesis. 443 (1–2): 129–138.
doi:
10.1016/s1383-5742(99)00015-0.
PMID10415436.
^Kuhnle, G.G.C.; Bingham, S.A. (1 November 2007). "Dietary meat, endogenous nitrosation and colorectal cancer". Biochemical Society Transactions. 35 (5): 1355–1357.
doi:
10.1042/BST0351355.
PMID17956350.
^Liu SJ, Huang PD, Xu JM, Li Q, Xie JH, Wu WZ, Wang CT, Yang XB (2022). "Diet and gastric cancer risk: an umbrella review of systematic reviews and meta-analyses of prospective cohort studies". Journal of Cancer Research and Clinical Oncology. 148 (8): 1855–1868.
doi:
10.1007/s00432-022-04005-1.
PMID35695929.
S2CID249613718.