A new study was published this week in the scientific journal Cancer discovery, made it possible to identify the specific characteristics of DNA damage caused by a diet very rich in red meat.
It actually incriminates the latter as a carcinogen, while opening the way for early detection of disease or the development of new treatments.
It’s not about stopping red meat: I recommend moderation and a balanced diet
, says Marius Giannakis, an oncologist at Dana-Farber Cancer Institute.
Scientific studies have so far proven a link between colorectal cancer and red meat consumption by asking people with this cancer about their eating habits.
However, this type of work is highly dependent on the data on which it is based. In 2019, a team of researchers sparked controversy by claiming that it is not entirely certain that reducing red meat consumption would reduce cancer mortality.
If we say that red meat causes cancer, […] There must be a mechanism causing this.
After all, scientists have long discovered how cigarette smoke causes cancer and how some UV rays penetrate the skin to cause genetic mutations that control how cells grow and divide.
So Marius Giannakis and his colleagues sequenced the DNA of 900 colorectal cancer patients, chosen from a pool of 280,000 people who participated in studies over several years, including questions about their lifestyle.
The strength of this approach is that participants could not have known that they would develop this cancer, unlike when they are resorted to questioning eating habits once the disease has started.
A type of mutation called alkylation
The analyzes revealed a specific change that had not been detected before, and indicated a type of DNA mutation called alkylation.
Not all cells with this mutation would necessarily become cancerous, as it was also present in healthy samples.
However, this mutation was significantly associated with consumption of red meat (processed or unprocessed) prior to disease onset, while it was not associated with consumption of poultry, fish or other factors examined.
For red meat, chemicals can cause alkylation.
These compounds can be produced from iron, which is abundant in red meat, or from nitrates, which are often found in processed meat.
This mutation was also present in the distal colon, a portion of the colon that previous studies had indicated is strongly associated with colorectal cancer caused by eating red meat.
In addition, among the genes most affected by alkylation are those that, according to previous work, are most likely to give rise to colorectal cancer when mutated.
All of these elements make up a strong case, as in detective work, according to Marius Giannakis.
Patients with the highest level of alkaloid tumors were 47% more likely to die than those without.
Only tumors from patients who consumed more than 150g of red meat per day showed high degrees of alkylating.
Identification of patients susceptible to alkylosis
For the researcher, this discovery could help clinicians identify patients who have a genetic predisposition to alkalosis, in order to specifically advise them to limit their consumption of red meat.
In addition, the fact that people who started accumulating these mutations are identified can help detect those most at risk of developing such a cancer or detect the disease much earlier.
Additionally, because the level of alkylosis appears to be a marker of disease severity, it can be used to provide a diagnosis of the life expectancy of those who have it.
Understanding how colorectal cancer develops also paves the way for designing treatments to interrupt or reverse this process, to prevent the disease from starting.