Since the International Agency for Research on Cancer, an agency of the World Health Organization, in 2015 classified red meat (beef, pork, veal, mutton, etc.) “probable carcinogen” and processed meat (cold cuts, sausages, etc.) “proven carcinogenic”, the risk associated with the consumption of high quantities of red meat of developing certain cancers, in particular colorectal cancer, is no longer in doubt.
But the debate remains open among scientists on the biological mechanism involved: is meat as such the cause of these cancers, in particular through the heme iron it contains? Can the nitrite additives, added in the transformation processes of a large number of cold cuts, promote the formation of tumors? Or can other factors related to the cooking of food, or the lifestyle of individuals, come into play?
A study published Thursday, June 17 in the journal of oncology Cancer Discovery, a journal with a strong academic impact factor, has just brought an important stone to the understanding of the process in play. For the first time, researchers from the Harvard School of Medicine, in the United States, have put evidence of the existence of a genetic signature specifically linked to a high consumption of red meat. By relying on three large American epidemiological monitoring cohorts, which have compiled data from 280,000 people since the 1970s-1980s, the Harvard team initially sought to identify “The different genetic fingerprints that are observed in colorectal tumors”, says Carino Gurjao, a French researcher at the Dana-Farber Cancer Institute and the first author of the article.
More than 150 grams per day
In total, data from 900 patients who developed colorectal cancer were used for this analysis. Colon cell DNA sequencing was performed on both healthy and cancerous samples. Since the patients studied had provided information on their eating habits since the start of their monitoring, the researchers were able to compare their observations on the DNA and the lifestyle of these individuals.
“This is the first time that we have had a database of this size, which made it possible to combine the study of DNA and diet”, continues Mr. Gurjao, who said to himself “Surprised to find an alkylating signature in these cells [une altération du génome], which is the expected genetic signature of nitrosated compounds ”. Nitrosated compounds lead directly to the trail of red meat: they are due not only to hemoglobin in the blood, but also to additives nitrites in processed meats.
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