When the dishes come out of the dishwasher, they should do one thing above all – shine. But that could damage the intestines, as a Swiss research team now describes in a study. They found out that after a wash cycle in professional dishwashers, such as those used in restaurants or cafés, residues of the rinse aid remain on the plates and certain ingredients in them can damage the protective layer of the intestines.
The professional dishwashers are characterized by the fact that plates, cups and cutlery are cleaned and dried in a flash. To do this, the dirty dishes are briefly rinsed under high pressure and washed off in a second cycle with water and rinse aid. However, many of the commercial dishwashers do not have an additional cycle that would remove the residues of the rinse aid, says study leader Cezmi Akdis, UZH Professor of Experimental Allergology and Immunology and Director of the SIAF in a statement.
According to the research team, toxic substances can remain on the plates and get into the gastrointestinal tract the next time you eat. And that could have a negative effect on your health.
With their study, the scientists therefore examined how the ingredients of commercial dishwashing detergents and rinse aids affect the intestinal epithelium. This is a protective layer in the gut – more specifically, a layer of cells that lines the inside of the gut. It controls what goes inside the body.
“We assume that defective epithelial barriers play a role in the development of two billion chronic diseases,” says study leader Cezmi Akdis. According to the epithelial barrier hypothesis, damage to the protective layer in the intestine can promote the development of many (chronic) diseases. Chronic depression, gastritis and multiple sclerosis, among others.
What does all this have to do with detergent and rinse aid? Researchers suspect that various substances can damage the intestinal epithelium. The scientists used a new technology to investigate whether this also applies to the ingredients of dishwashing liquid and rinse aid. They did research on gut organoids and gut cells on microchips. Organoids are small pieces of tissue that can be grown in the laboratory and are very similar to many organs. In this case, the tissue resembled a human intestinal epithelium.
They exposed them to tiny amounts of diluted dishwasher and rinse aid – in a concentration that should correspond to what people ingest from leftovers on machine-washed plates and bowls. The scientists carried out microbiological examinations. The result: in small doses, the rinse aid causes the protective layer of the intestine to become more permeable. More specifically, an ingredient in the rinse aid was responsible for this reaction – alcohol ethoxylate. It is a surfactant, i.e. a washing-active substance.
“The effects we have detected can signal the onset of disruption of the intestinal epithelium and of many chronic diseases,” summarizes the study leader. Further studies are still needed to know the exact effect of the ingredients on humans and to investigate the health risks of alcohol ethoxylates in more detail.
Sources: Study, Study communication, Epithelial barrier hypothesis communication
