Food additive E551 may promote the development of coeliac disease

E551, more commonly known as silica dioxide, is a powder consisting of nanoparticles (particles smaller than 100 nm) used as an anti-caking additive in dry or powdered foods such as soups, spices, cereal-based infant formula, instant coffee and chocolate products, and freeze-dried pasta. It is found in the list of ingredients of more than 2,600 food products worldwide. It prevents the formation of lumps, preserving the taste, texture and stability of foods. This additive is also widely used as a processing aid and is essential in food processing stages. In this case, it does not appear in the list of ingredients used in the recipe, but is still present in the final product. Humans are therefore exposed to low doses of E551 on a daily basis through their diet.

Researchers at INRAE, in collaboration with McMaster University in Canada, therefore investigated the potential impacts of this exposure on the intestinal immune system. More specifically, they explored its effect on oral tolerance to food proteins. This is an essential function for nutrition, which consists of blocking inflammatory immune reactions against the proteins in the food we eat by triggering a tolerogenic response in the intestine. It is established from the very beginning of life, and its disruption is the first step in the development of an allergy (peanuts, cow's milk, fish, shellfish, eggs, etc.) or gluten intolerance, such as coeliac disease.

Coeliac disease is an autoimmune disease linked to the ingestion of gluten (a protein found in many cereals such as wheat, rye and barley) in people with a genetic susceptibility. It is characterised by inflammation of the intestine, abdominal pain and diarrhoea, and can lead to weight loss and deficiencies in patients. The incidence of this disease continues to increase worldwide, without a complete understanding of the mechanisms responsible. Here, researchers have shown in mice that daily exposure to E551 for 3 months reduces the development of tolerance to dietary proteins and promotes the induction of intestinal inflammation, evidence of intolerance. How? Exposure to this additive reduces the number of intestinal immune cells producing anti-inflammatory molecules necessary for maintaining food tolerance. Using a mouse model genetically similar to coeliac patients, the researchers then showed that daily treatment with E551 aggravates the inflammatory signs characteristic of this chronic disease.

This study supports the hypothesis that chronic exposure to dietary E551 could act as a component promoting the development of coeliac gluten intolerance in genetically susceptible individuals.

This research is the first to identify a potential toxic hazard associated with this additive, which until now was considered safe for use in food. In order to ensure that this potential hazard could ultimately be taken into account in the assessment of the risk of human consumption of E551, the researchers used exposure protocols that took into account the expectations of European and North American food safety agencies (European Food Safety Authority, Health Canada), working with human doses, over the long term and with the additive incorporated into food.

¹ https://world-fr.openfoodfacts.org/additif/e551-dioxyde-de-silicium

² These results are from the ANR PAIPITO project, Food Particles: Inflammation, Intestinal Pathologies and Oral Tolerance (2017-2020). The team is continuing its work through several funded projects, in partnership with the French National Metrology and Testing Laboratory (LNE), the CNRS and INSERM, which are ongoing until 2027.