Anti-caking agent: Food additives affect the gut's immune system
The anti-caking agent silicon dioxide E551 has been used in the food industry for decades and was previously considered harmless. However, Swiss scientists have now discovered that these tiny nanoparticles can affect the gut's immune system.
Additives in processed foods
The food industry is relying on more and more additives in processed foods. Even for organic food, more and more of these substances are approved. The respective substances should serve, among other things, to extend the shelf life, protect against unwanted color changes, improve the consistency, avoid the addition of sugar or standardize the color of the product. A widely used additive is E551 silica. Although this was long considered to be harmless, scientists have now found that it can have an impact on the intestinal immune system.
E551 has long been considered harmless
Anti-caking agents ensure that dry foods such as ready-made soups, instant coffee or seasoning powder remain free-flowing.
One such agent is E551 silica. The ultrafine powder obtained from quartz sand has been widely used in the food industry for 50 years and was previously considered harmless.
But now scientists from the Swiss National Research Program “Opportunities and Risks of Nanomaterials” have discovered that these nanoparticles can influence the gut's immune system.
Inflammation-like reaction started
"Previously, it was assumed that these nanostructured particles were completely inert," said Hanspeter Nägeli from the Institute of Pharmacology and Toxicology at the University of Zurich in a message.
But now he and his colleagues have found that these particles are able to activate certain immune cells.
"We have shown that resting dendritic cells are stimulated in contact with nanosilica and trigger an inflammation-like reaction," said Nägeli.
The results, which have been published in the journal “Particle and Fiber Toxicology”, are particularly interesting because dendritic cells play a crucial role in the intestinal immune system: they maintain the dynamic balance between defense reactions and tolerance.
The dendritic cells are significantly involved in the fight of the immune system against pathogens and foreign bodies. But they also coordinate the benevolent response to food components or representatives of the normal intestinal flora.
Bowel diseases depend on various factors
As has been shown in experiments with mouse cell cultures, the dendritic cells take up the nanosilica inside their cells. That wakes her from her sleep. They start to excrete a certain inflammatory signaling molecule.
However, the researchers do not know whether such processes may also shift the immunological balance of the human intestine towards increased defense.
But their results could explain the observation that inflammatory bowel disease spreads as more people consume finished products.
“It's not about stoking fear. Inflammatory bowel diseases depend on a variety of factors, ”said Nägeli. And nanosilica in food makes up at most a small piece of the puzzle in the overall picture of these complex diseases.
Nevertheless, Nägeli recommends greater caution when handling these particles in the diet due to his results. "Their massive use has to be reconsidered," the researchers write in their article.
Criticism of the current safety assessment
In another technical article in the "Journal of Nanobiotechnology", Nägeli criticizes the current safety assessment of Nanosilica.
"No immunological criteria are raised in the toxicological analyzes," said the expert. In addition, liver damage was observed in the feeding experiments with rats at the highest dose - but was not taken into account in the risk evaluation.
A connection with nanosilica has not been proven, but it cannot be ruled out based on current knowledge. "We therefore advocate the application of the precautionary principle and the review of the limit value in food," said Nägeli. (ad)