2024-02-15 14:10:12
Emulsifiers are food additives very commonly present in food products in France. In 2023, work based on the NutriNet-Santé cohort highlighted the existence of a link between their consumption and the risk of cardiovascular disease. For the first time, new work published in the journal PLoS Medicine suggests the existence of a link between consumption of emulsifiers and increased risk of cancer.
Mathilde Touvier, who heads the nutritional epidemiology research team (Eren, Inserm/Inrae/CNAM/Université Sorbonne Paris Nord/Université Paris Cité), and Bernard Srour, epidemiology researcher in the same team, coordinator of the Physical Activity Nutrition Network cancer research (NACRe Network), coordinated this work, as part of the NutriNet-Santé study. They decipher these new results.
The Conversation: Can you explain to us what emulsifiers are used for?
Mathilde Touvier : The role of emulsifiers is to obtain certain textures in industrial foods, to add creaminess, and to allow the stability of the mixtures obtained over time. Thus, the shelf life is extended, and the products can stay on the shelves longer without losing their properties.
Emulsifiers are found in many products, from desserts (madeleines, cakes, ice creams, etc.) to prepared meals, including chocolate bars, margarines, industrial sauces, etc. Furthermore, some of these additives are even found in products that the consumer could judge as “healthy”, such as low-fat margarines, often perceived as a better alternative to butter, or certain brands of rusks or yogurts.
There are many types of emulsifiers: mono- and diglycerides of fatty acids, carrageenans (polysaccharides obtained from red algae), modified starches, lecithins, phosphates, celluloses, gums, pectins…
Their presence in foods varies greatly from one brand to another, even for the same type of product. For example, vanilla ice cream from a certain brand may contain it, while that from another brand may not.
The Conversation: You have studied the links with the cancer risk of several dozen emulsifiers found in consumer products. Concretely, how did you proceed?
Bernard Srour : We measured exposure to almost sixty additives, around thirty of which were consumed by at least 5% of the population. To do this, we worked as part of the NutriNet-Santé cohort study. We first estimated the intake of food additives such as emulsifiers in the diet of the participants, then we carried out an epidemiological study to determine whether there was a statistical link between these additives and the development of cancers.
More than 92,000 people were selected, one of the conditions being that they did not have cancer before their inclusion nor during their first two years of follow-up in the cohort. Their eating behaviors were assessed by detailed and repeated questionnaires, in order to determine their consumption habits. When a participant declared having consumed a food of a given brand, we listed the elements composing this food in order to determine the food additives it contained.
To do this, we crossed several databases, in particular that of Open Food Facts, a collaborative database, as well as the OQALI database (Observatory of Food Quality, a national database managed by the National Institute of Agricultural Research and the Environment (INRAE) and the National Agency for Food, Environmental and Occupational Health Safety (ANSES)), and that of Mintel Global New Products Database (GNPD). This allowed us in particular to follow changes in the composition of foods over time, when certain formulations were modified by manufacturers.
Beyond these qualitative aspects, we also carried out dosages, or benefited from those which had been carried out by other structures (in particular by the European Food Safety Agency (EFSA) or the consumer association UFC – What to choose).
To limit the risk of bias, we also, of course, took into account factors such as age, sex, body mass index, alcohol consumption, smoking status, practice of physical activity. … A large number of nutritional parameters were also taken into account (energy intake, sugar, salt, share of “ultra-processed” foods in the diet, consumption of sweeteners, etc.), in order to take into account the overall quality of the diet, so that we cannot say that this effect could be the consequence of general “junk food”.
The Conversation: Your results indicate a link between certain emulsifiers and an increased risk of certain cancers. Which ?
Mathilde Touvier : We observed associations between a higher intake of some of these additives, notably mono- and diglycerides of fatty acids (E471) or carrageenans (E407 and E407a), and an increased risk of different cancers.
In this case, for E471, the highest consumers in this study (3rd tertile of consumption) had an increased risk of cancer of all types of around 15%, compared to the lowest consumers (first tertile). The associations were more specifically observed for breast cancer and prostate cancer.
No stable association was detected between emulsifier consumption and colorectal cancer risk in this study, but statistical power was limited for this cancer site. It will therefore be important to reproduce these analyzes in a few years, with a greater duration of follow-up and a greater number of cases.
Concerning carrageenans, the associations seem to concern breast cancer more specifically. The highest consumers of E407 had a 28% higher risk compared to the lowest consumers.
The Conversation: Do we have any idea why these additives are associated with a greater risk of cancer? Any hypotheses on their modes of action?
Mathilde Touvier : In an epidemiological study such as ours, the objective is to detect associations, but it is difficult to extrapolate to “guess” the underlying mechanisms from these analyzes
There could be a “class” effect, which would be linked to the “family” of emulsifiers, and therefore to the emulsion mechanism, however given that we do not see an association between the total quantity of emulsifiers and the risks of cancer in this analysis, this hypothesis does not seem the most likely.
On the other hand, our toxicology colleagues will now have to try to explain why certain substances such as carrageenans seem to have a more important role than others. Some possible explanations already exist.
We know, for example, thanks to the work of the team of Benoît Chassaing, co-author of our article, that certain emulsifiers disrupt the intestinal microbiota as well as certain metabolic parameters, which results in particular in inflammatory phenomena.
But there is still much to discover and understand.
Bernard Srour : We have planned a more mechanistic component in this project, because in the NutriNet-Santé cohort, in addition to nutritional data, we have a collection of biological fluids (urine and plasma) for nearly 20,000 participants. In these samples, we measured metabolic markers, inflammation markers and oxidative stress markers.
In the next stages of the project, we will look at whether the associations observed with cancer, and those previously highlighted with cardiovascular diseases, can be explained by disturbances at the level of these markers.
The idea would be to better understand through which biological mechanistic pathways the ingestion of these additives can influence the risk of cancers and cardiometabolic diseases. Stool samples are also being taken to analyze the intestinal microbiota.
Let us also emphasize that as this is a multidisciplinary project, it is the results obtained by toxicologists on certain emulsifiers which led us to take an interest in these additives. Other work is underway, in particular to test how mixtures of these additives could have links with health, through epidemiological and experimental approaches.
It is by assembling these different pieces of the puzzle, cohort studies, experimental studies, and short-term interventional studies in humans if possible, that we can hope to one day obtain a global image of the effects of these molecules on health. .
The Conversation: What are the limitations of this study?
Bernard Srour : The cohort was mainly made up of women (79%), and the participants had an average age of 45 years, as well as a higher than average level of education (therefore paying more attention to their diet), which limits the possibility of generalizing these results to the entire population. Furthermore, in this type of epidemiological studies, despite taking into account a large number of so-called confounding factors (such as age, smoking status, etc.), the causal link cannot be directly established. To get the full picture, further studies will be needed.
The Conversation: While waiting to know more, what would be the course of action? Can we do without these additives, and if so, should the regulations be reviewed?
Mathilde Touvier : Emulsifiers are not essential, in the sense that they are not there to guarantee the microbiological safety of products, for example. They aim above all to facilitate manufacturing processes, and to ensure the stability of these mixtures over time.
It is possible to do without it, since some brands do it.
Currently, although we are not yet at a strong level of proof, we note that a certain number of presumptions are accumulating, at the experimental level as well as at the epidemiological level, regarding their effects on health. In light of these new elements, the question that arises for authorities such as the European Food Safety Authority (EFSA) is: “At what point do we act?” »
As a consumer, in general, the best is to apply what is already in the national nutrition and health program (PNNS): limit ultra-processed foods, and limit foods containing “cosmetic” additives such as being emulsifiers.
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