Study links food additive mixtures to increased risk of type 2 diabetes

Food additive mixtures are an everyday feature of our diets, especially through ultra-processed foods. Until recently, safety evaluations of these additives have been conducted substance by substance due to a lack of data on the effect of them ingested together. In a new study, researchers from Inserm, INRAE, Sorbonne Paris Nord University, Paris Cité University and Cnam, as part of the Nutritional Epidemiology Research Team (CRESS-EREN), examined the possible links between exposure to mixtures of commonly consumed food additives and the onset of type 2 diabetes. They analysed the health data of over 100 000 adults participating in the French NutriNet-Santé cohort. Two out of the five mixtures tested were found to be associated with a higher incidence of type 2 diabetes, particularly one mixture containing different emulsifiers such as carrageenans, modified starches and other additives (found in stocks, milky desserts, fats and sauces, etc.), and another containing sweeteners, colourings and acidifiers (characteristic of artificially-sweetened drinks and sodas). Their findings have been published in Plos Medicine.

Widely used by the agri-food industry, food additives are mainly found in the ultra-processed products sold in our supermarkets. The scientific literature now provides information on the potential harmful effects of consuming several of these substances, which have been associated with the development of metabolic disorders, chronic inflammation and gut microbiome imbalance. Recent studies from the NutriNet-Santé cohort have also revealed an association between the consumption of some of these additives and an increased risk of type 2 diabetes, cancer and cardiovascular diseases.

Although these studies provide insights into the individual effect of each of these substances, no study had yet looked at the possible impact of their combined consumption. And this is despite ultra-processed foods often containing mixtures of food additives, each with its specific properties (preservatives, flavour enhancers, colourants, texture agents, etc.).

To measure the consequences of exposure to these mixtures, a research team led by Mathilde Touvier, Inserm research director and study coordinator, analysed the health data of 108 643 adults in the NutriNet-Santé cohort over an average follow-up period of 7.7 years.

The participants completed at least two days (up to 15 days) of online dietary records of all food and drink consumed and their brands.

In order to obtain a reliable estimate of the exposure to additives and to focus on those with a potentially significant health impact, only those additives consumed by at least 5% of the cohort were included in mixture modelling. The presence or absence of each additive in each food was determined by cross-referencing several databases, taking into account the date of consumption (to incorporate any reformulations over time), as well as some laboratory assays of quantitative levels of additives in the food.

Five main mixtures of additives were identified, representing groups of substances frequently ingested together (due to their joint presence in industrially processed products or resulting from the co-ingestion of foods often consumed together).

The results show two of these mixtures to be associated with a higher incidence of type 2 diabetes, regardless of the nutritional quality of the diet (intake of sugar, calories, fibre, saturated fat, etc.) and sociodemographic and lifestyle factors. No associations were found for the other three mixtures.

The first mixture incriminated was primarily composed of several emulsifiers (modified starches, pectin, guar gum, carrageenans, polyphosphates, xanthan gum), a preservative (potassium sorbate) and a colouring agent (curcumin). These additives are typically found in a variety of ultra-processed foods, such as stocks, milky desserts, fats and sauces.

The other mixture implicated was primarily composed of additives found in artificially-sweetened drinks and sodas. It contained acidifiers and acidity regulators (citric acid, sodium citrates, phosphoric acid, malic acid), colouring agents (sulphite ammonia caramel, anthocyanins, paprika extract), sweeteners (acesulfame-K, aspartame, sucralose), emulsifiers (gum arabic, pectin, guar gum) and a coating agent (carnauba wax).

In this study, interactions between the additives of these mixtures were detected suggesting that some could interact with each other, either by enhancing their effects (synergy) or by attenuating them (antagonism).

This study is the first to estimate exposure to food additive mixtures in a large cohort of the general population and to analyse their link to the incidence of type 2 diabetes. The findings suggest that several emblematic additives present in many products are often consumed together and that certain mixtures are associated with a higher risk of this disease. These substances may therefore represent a modifiable risk factor, paving the way for strategies to prevent type 2 diabetes," explains Marie Payen de la Garanderie, PhD student at Inserm and first author of this research.

"Further studies are needed to elucidate the underlying mechanisms and deepen the understanding of the potential synergies and antagonisms between these substances. This observational study alone is not sufficient to establish a causal link. However, our findings are in line with recent in vitro experimental work suggesting possible cocktail effects. They indicate that the evaluation of additives should take into account their interactions and support public health recommendations that advise limiting non-essential food additives," explains Dr. Touvier.

NutriNet-Santé is a public health study coordinated by the Nutritional Epidemiology Research Team (CRESS-EREN, Inserm/INRAE/Cnam/Sorbonne Paris Nord University/Paris Cité University) which, thanks to the commitment and loyalty of over 180 000 participants (known as Nutrinautes), advances research into the links between nutrition (diet, physical activity, nutritional status) and health. Launched in 2009, the study has already given rise to over 300 international scientific publications. In France, a drive to recruit new participants is still ongoing in order to continue to advance public research into the relationship between nutrition and health.

By devoting a few minutes per month to answering questionnaires on diet, physical activity and health through the secure online platform etude-nutrinet-sante.fr, the participants contribute to furthering knowledge towards a healthier and more sustainable diet.