A scientific study (Crowe et al., 2022) published in Science of Food(a partner of Nature) shows that consumption of processed meats with nitrites and nitrates is a trigger for colorectal cancer. (1)
The presence of nitrites and nitrates added as preservatives in sausages, frankfurters and other processed meats, already the focus of heated political debate in France, is now also being discussed in the UK. (2)
Nitrites in meats and colorectal cancer risk, the British study
British researchers-including Professor Chris Elliott, a leading expert on food safety and food chain integrity-included in the diet of three groups of colorectal cancer mice a ration equal to 15 percent of:
– Nitrite-free pork, viz.
– nitrite-free sausage, or
– Nitrite-containing sausage (frankfurter).
The 15% supplementation is a rather high dose, compared to the average actual consumption of meat products, but it is well below the 50% ration of meat with nitrite adopted in similar previous studies.
The results
After 8 weeks, the researchers checked the evolution of the disease, observing that the guinea pigs fed the nitrite-containing frankfurters showed significantly higher tumor growth, +53%, than the other groups of guinea pigs.
The group fed the nitrite-containing sausages also showed.
- Higher levels of oxidative stress,
- the presence (only in this group) of trimethylamine N-oxide (TMAO), a metabolite already associated with the development of colorectal cancer,
- A reduced microbial diversity in the gut microbiota.
Stop nitrates in processed meats
‘The results of this study clearly show that not all processed meats carry the same risk of developing CRC (colorectal cancer, ed.),’ the study authors conclude.
The most responsible industries-in Italy and France especially-have already eliminated nitrites and nitrates, as noted. (3) With outstanding results, such as most recently Primo salami-nitrite- and nitrate-free-from the Veneto-based Brugnolo salumificio.
The harmful process of nitrites
Sodium and potassium salts of nitrites (E249 to E250) and nitrates (E251 to E252) are added as preservative additives, to
- prevent the growth of harmful microorganisms, such as Clostridium botulinum (responsible for the very dangerous botulism), and
- Maintain the rosy color of the meat.
Moreover, nitrates and nitrites are naturally occurring chemical compounds, not harmful per se. Nitrates are not even affected by biological processes, but when ingested they are soon transformed into nitrites by bacteria in the oral cavity.
Nitrites are more reactive. When they reach the acidic environment of the stomach and come in contact with a source of secondary amines (abundant in protein foods) they can result in the formation of nitrosamines.
The health hazards
These substances are carcinogenic and mutagenic, that is, capable of damaging DNA. And they are also formed in foods cooked at high temperature, as well, as seen. (4)
An additional toxicological risk related to the intake of significant doses of nitrite is methemoglobinemia, a metabolic disorder characterized by the inability of hemoglobin (Hb), oxidized to methemoglobin (metHb), to bind and transport oxygen. (5)
Marta Strinati
Notes
(1) Crowe, W., Pan, X., Mackle, J. et al. Dietary inclusion of nitrite-containing frankfurter exacerbates colorectal cancer pathology and alters metabolism in APCmin mice. npj Sci Food 6, 60 (2022). https://doi.org/10.1038/s41538-022-00174-y
(2) Marta Strinati. Nitrites in cured meats, the Court of Appeal of Aix-en Provence agrees with Yuka. GIFT (Great Italian Food Trade). 10.12.22
(3) Marta Strinati. Nitrites and nitrates in cured meats. Market study and analysis. GIFT (Great Italian Food Trade). 30.4.22
(4) Dario Dongo, Ylenia Patti Giammello. Nitrites, nitrates and nitrosamines, EFSA revises risk analysis. GIFT (Great Italian Food Trade). 19.10.22
(5) Osvaldo Matteucci, Gianfranco Diletti, Vincenza Prencipe, Elisabetta Di Giannatale, Maria Maddalena Marconi & Giacomo Migliorati. Two cases of acute methemoglobinemia due to suspected sodium nitrite poisoning. Veterinaria Italiana, 44 (2), 439-445 © IZS A&M 2008 Vol. 44 (2), Vet Ital 439 https://www.izs.it/vet_italiana/2008/44_2/439.pdf
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
