While we now know that eating red and processed meat is associated with an increased risk of colorectal cancer, what about other cancer locations? A new study, conducted using data from volunteers in the NutriNet-Santé cohort, highlights a potentially more global effect of eating these products.
Following meta-analyses, international collective expert bodies - in particular, the International Agency for Research on Cancer (specialized agency of the World Health Organization), the World Cancer Research Fund International, and the French National Cancer Institute - have concluded that the risk of developing colorectal cancer is increased by the excessive consumption of red meat and processed meats. It is based on these findings that, in April, the French High Council for Public Health (HCSP) recommended that people should eat no more than 500 g of red meat (beef, veal, pork, lamb, wild boar, etc.) and no more than 150 g of processed meat per week.
Red and processed meat implicated in other types of cancer?
However, are the effects of eating red and processed meat limited to the development of colorectal cancers? A few studies concerning other types of cancer suggest that this may not be the case. In particular, based on data from the SU.VI.MAX cohort, in 2014 the nutritional epidemiology research team (EREN) observed a significant effect of processed meat intake on the incidence of breast cancer. This cohort of 13,000 people was initially intended to study the impact of antioxidant vitamin and mineral supplementation on health. "Our study concerned the some 4,700 women in the SU.VI.MAX cohort", specifies Dr Mathilde Touvier*. "We wanted to find out more about the issue, performing analyses on a larger cohort that would help us identify any impacts on other types of cancer."
Recently, these researchers have published the results of a study conducted on the NutriNet-Santé cohort, including 61,476 people and over 1,600 cases of incident cancer between 2009 and 2015. Aimed at studying the effects of diet on the health of French people, NutriNet offers the advantage of supplying very detailed information on participants’ eating habits. Every 6 months, participants provide a detailed account of everything they have eaten over a 3-day period (all the food and drink they have consumed, as well as portion sizes). A composition table is used to convert these food intakes into nutritional intakes.
The results published in the International Journal of Cancer show that the risk of developing breast cancer increases with red meat intake, and that this association exists more generally for the overall cancer risk. Hence, in the 20% of people eating the most red meat (close to 100 g/day on average) the cancer risk is 30% higher than it is in the 20% of people eating the least red meat (40 g per day on average).
Could a diet high in antioxidants be the antidote?
Another lesson to emerge from the SU.VI.MAX cohort was that antioxidant supplementation may compensate - at least partially - for the impact of eating red and processed meat on the development of cancer. Hence, no link was found between red meat intake and breast cancer in the women having taken antioxidant supplements. However, in the group having taken a placebo, this association is observed and is linear: the more red meat is consumed, the higher the risk. This result is consistent with the protective effects of antioxidants found in mice by researchers from Inra (Toxalim unit in Toulouse).
The objective of the EREN researchers is now to determine whether a diet naturally high in antioxidants also provides this protective effect. To do this, the researchers are first of all working to construct an indicator of the antioxidant potential of the diet, based on a description provided by the participants of their food intake. This indicator will then be used to test the impact of an antioxidant-rich diet on the risk of cancer associated with eating meat.
Join the NutriNet-Santé study
If you want to help further our understanding of the effects of diet on health, it’s easy. Simply enroll on the website and complete the online questionnaires (maximum of one per month). This cohort, opened in 2009, now has over 160,000 “nutrinauts”. Welcome to all the new volunteers joining the adventure!
*Inserm U1153/Inra/ Cnam/ University of Paris 13 – Center of Research in Epidemiology and Statistics Sorbonne Paris Cité
A. Diallo et coll., Red and processed meat intake and cancer risk : results from the porspective NutriNet-Santé cohort study, Int. J. Cancer, édition en ligne du 15 septembre 2017