Allergies, digestive disorders… For several years now, preservatives have had a bad reputation. Longer-term effects on metabolism have even been mentioned, such as a disrupted microbiota. This Thursday, two new studies go even further, suggesting an association between the consumption of certain preservatives and an increased risk of cancer and type 2 diabetes. Professor Boris Hansel, endocrinologist-nutritionist, analyzes the results of this work for True Medical.
Preservatives responsible for cancer and type 2 diabetes
Preservatives are present almost everywhere in our daily lives (in candies, biscuits, cold meats, alcoholic drinks, but also certain frozen meals). Among the three and a half million foods and drinks listed in the Open Food Facts World database in 2024, more than 700,000 contain at least one of these substances. These additives, due to their characteristics, make it possible to extend the shelf life of foods. However, experimental research has indicated that some preservatives may harm cells and DNA, as well as have negative effects on metabolism. However, the connections between these substances and the risk of developing cancer or type 2 diabetes are not yet clearly established.
Researchers from Inserm, Inrae, Sorbonne Paris Nord University, Paris Cité University and Cnam have undertaken to examine these links through a unique study. They relied on health and food consumption data from more than 100,000 adults participating in the NutriNet-Santé cohort study.
In detail, participants had to provide information on their health, lifestyle, physical activity and eating habits, in particular indicating the brands of industrial products consumed over several 24-hour periods. These data were cross-referenced with several food bases and supplemented by measurements making it possible to estimate the exposure of volunteers to preservatives.
In total, 58 preservatives and antioxidant additives were identified, 17 of which could be analyzed individually because they were consumed by at least 10% of the participants. To limit possible bias, the analyzes took into account the socio-demographic profiles of the participants, their tobacco and alcohol consumption, the nutritional quality of their diet, etc.
Increased risk of cancer
The risk of cancer, highlighted in the review The BMJ, was confirmed by researchers: “During the follow-up period, 4,226 participants (of the 105,260 participants in this study) were diagnosed with cancer, including 1,208 breast cancers, 508 prostate cancers, 352 colorectal cancers, and 2,158 other cancers,” they recognize.
In detail:
- Sorbates, particularly potassium sorbate, increased the overall risk of cancer by 14% and that of breast cancer by 26%;
- Sulfites were associated with a 12% increase in overall cancer risk;
- Sodium nitrite was associated with a 32% increased risk of prostate cancer, while potassium nitrate was associated with an increased risk of general cancer (13%) and breast cancer (22%);
- Acetates were also associated with a higher risk of overall cancer (15%) and/or breast cancer (25%), while acetic acid was associated with a 12% increase in overall cancer risk.
“Among antioxidant preservatives, only total erythorbates and specific sodium erythorbate were found to be associated with a higher incidence of overall (12%) and breast (21%) cancer.“, the researchers further specify.
Increased risk of type 2 diabetes
Between 2009 and 2023, 1,131 cases of type 2 diabetes were identified among the 108,723 study participants.
Results: Higher consumptions of overall preservative additives, non-antioxidant preservatives, and antioxidant additives were associated with an increased incidence of type 2 diabetes, 47%, 49%, and 40%, respectively, compared to lower levels of consumption.
Concretely, of the 17 conservatives studied individually, “higher consumption of 12 of them is associated with an increased risk of type 2 diabetes.”
Potassium sorbate (E202), citric acid (E330), sodium nitrite (E250), acetic acid (E260) and even rosemary extracts (E392) have, among others, been implicated.
What can we learn from this work?
If the results of these two studies must be confirmed, Anaïs Hasenböhler, doctoral student at Eren, affirms that this is a real step forward: “c“The new data adds to other evidence supporting a reassessment of regulations governing the general use of food additives by the food industry in order to improve consumer protection.”
“These are the first two studies in the world on the links between preservative additives and the incidence of cancer and type 2 diabetes. Although the results of these two studies require confirmation, they are consistent with experimental data suggesting harmful effects of several of these compounds,” confirms Mathilde Touvier, Inserm research director and coordinator of this work. “This work once again justifies the recommendations of the National Health Nutrition Program made to consumers to favor fresh and minimally processed foods and to limit unnecessary additives as much as possible. she adds. In other words, favoring fresh and minimally processed foods.
Conclusions shared by Professor Boris Hansel, endocrinologist-nutritionist, although they deserveto be nuanced“.
“Epidemiology draws associations, not conclusions”
In view of these results, the doctor first urges a certain amount of restraint. “Epidemiology draws associations, not conclusions”he recalls.
Indeed, the majority of studies that show associations are not confirmed as causal. “We must always remain nuanced and not draw conclusions from each study that comes out, otherwise the majority of foods in our daily lives would be prohibited.”he emphasizes.
Existing preclinical studies then say several things.
When preservatives are consumed, insulin-sensitive organs, such as the muscles or liver, show a small decrease in their response. “We also see links with inflammation, and this inflammation can promote diabetes. So there are plausible mechanisms.”says Professor Boris Hansel, present on Instagram @pumsuniv_boris_hansel.
As for cancers, the responsibility of nitrites has a relatively high level of proof. “Many elements confirm this. Moreover, the International Agency for Research on Cancer has classified processed meats as certain carcinogens. This is the highest level of proof, which justifies reducing their presence”he attests.
For all other preservatives, the doctor wishes to exercise caution: other epidemiological studies indicate risks of specific cancers, “but these are not studies which allow us to assert any causality”.
Preservatives: how to limit their daily effects?
Faced with this new data which confirms existing nutritional recommendations, Mathilde Touvier, principal investigator of the NutriNet-Santé cohort and Inserm Research Director, advises favoring unprocessed or minimally processed foods. “The free application like Open Food Facts can also help in this sense: it provides the Nutri-Score, reveals the list of additives used…”, she specifies.
Same refrain from the endocrinologist, who however invites everyone not to change their habits, but simply to reduce the number of industrial foods consumed.
“You cannot completely remove processed foods from your diet. However, it is possible to limit them. A 10% reduction in processed foods corresponds to a 10 to 20% reduction in risks”he confides, before adding that diet is not the only risk factor. A sedentary lifestyle, lack of sleep and alcoholic beverages are all elements to take into account.
“We don’t talk enough about alcohol, which kills, nor about fruits and vegetables which protect“, underlines the specialist, before concluding”for consumers, the message must remain simple and fundamental. No need for an overload of nutritional information every day!“