Commercial dishwasher rinses often contain alcohol ethoxylate, which damages the intestinal epithelium, causing chronic illnesses.
Researchers at the Swiss Institute of Allergy and Asthma Research are working with organoids to investigate whether residue from rinse agents on dishes after being cleaned in professional-grade dishwashers can harm the gut's natural protective layer and contribute to chronic illnesses.
Commercial dishwashers are a handy way to clean and dry plates, glasses, and cutlery in many situations such as restaurants, schools, and barracks. However, a recent study by researchers at the University of Zurich (UZH) has shown that these appliances carry a danger.
"What's especially worrisome is that in many appliances, there's no additional wash cycle to remove the remaining rinse aid," says UZH professor of experimental allergology and immunology and director of the SIAF, who conducted the research. "This means that potentially hazardous substances remain on the dishes, where they can then be rinsed off the next time."
This motivated the Akdis research group to investigate what effects commercial-grade detergents and rinse agents have on the gut's epithelial barrier, which connects the intestinal tract and regulates what enters the body. Conditions such as food allergies, gastritis, obesity, cirrhosis of the liver, rheumatoid arthritis, chronic depression, and Alzheimer's disease are linked to a defect in this barrier.
Similar protective layers are also present on the skin and in the lungs. Many foods and substances we encounter everyday can deteriorate these layers, according to Akdis. “We assume that defective epithelial barriers are to blame for the onset of two billion chronic illnesses,” according to the hypothesis.
The researchers used a newly developed technology for their investigation – human intestinal organoids and intestinal cells on microchips. The tissue is a three-dimensional clump of cells that is very similar to the intestinal epithelium in humans. Commercial detergents and rinse aids have a significant impact on these cells. (1:10,000 to 1:40,000)
Researchers found that high amounts of rinse agents killed intestinal epithelial cells, while lower doses made it more permeable. Several genes and cell signaling proteins could also be involved in inflammatory responses, according to a more detailed analysis.
According to Akdis, these findings have significant implications for public health. "The effect that we discovered may indicate the start of the destruction of the gut's epithelial layer, and may lead to the onset of many chronic illnesses," says the researcher.
Ismail Ogulur, Yagiz Pat, Duygu Yazici, Beate Rückert, Yaqi Peng, Urszula Radzikowska, Patrick Westermann, Milena Sokolowska, Raja Dhir, Mubeccel Akdis, Kari Nadeau, and Cezmi A. Akdis, in J. J. & Clinical Immunology, 1 December 2022. DOI: 10.1016/j.jaci.202