Detergent Residue on Dishes Damages the Gut
A team of researchers was “shocked” to discover that commercial rinse aid residue remaining on washed and ready-to-use dishware—even after a full standard wash and rinse cycle in commercial dishwashers—can damage the gut barriers of diners eating off of the dishware [1], [2], [3].
If you’re familiar with my website, then you know that barrier disfunction is a big deal. A defective gut barrier, in particular, is associated with food allergies, gastritis, diabetes, obesity, cirrhosis of the liver, rheumatoid arthritis, multiple sclerosis, autism, chronic depression, and Alzheimer’s disease, among others [4].
So the capacity for our dishware to cause gut barrier disfunction should get our attention. Let’s take a closer look at the study and its findings.
“We assume that defective epithelial barriers play a role in triggering the onset of two billion chronic illnesses.”
This study focuses on commercial dishwashers and commercial dishwashing products [1].
Commercial dishwashers are widely used in restaurants, bars, coffee shops, and other public dining establishments around the world to clean and sanitize dishes in as little as one to three minutes. Typically, there is a wash cycle with a detergent, followed by a rinse and dry cycle with a rinse aid. Notably, there is no further wash cycle to remove the rinse aid—it is allowed to dry in place
So the research team hypothesized that detergent and rinse aid residues might remain on the surface of the dishware, with the potential to cause gut barrier disfunction. Sure enough, when the team simulated gut exposure to detergent and rinse aid in quantities comparable to residues remaining on ready-to-use dishware, they observed increased intestinal permeability and even cell death. As they began examining individual components and combinations of components, they honed in on commercial rinse aid—and alcohol ethoxylates, in particular—as the component responsible for the observed gut damage.
Alcohol ethoxylates are commonly used surfactants in detergents and rinse aids. And the study comments that we are continuously exposed to alcohol ethoxylates in home and personal care products, agrochemicals, paints, and coatings, among other products.
“[W]e found that a chemical compound used in commercial rinse aids remains as residue on washed and ready-to-use dishware, even after a full standard rinse cycle. Even the smallest amount of this compound kills cells and damages an unsuspecting diner’s epithelial barrier.”
Notably, even at a very small dilution rate of the rinse residue—a dose much lower than that which kills cells—the researchers observed upregulation of 427 genes associated with response to hazardous chemicals, epithelium cell development, and cell signaling and communication, as well as indications of inflammatory and immune responses. Thus, chronic exposure, even at very low doses, may play a role in disrupting the gut barrier.
In addition to commercial products, the researchers also investigated three household dishwasher detergents. Household detergents were found to cause damage to the gut barrier at certain concentrations; however, damage was not observed at the very diluted concentration expected to remain after a standard household dishwasher cycle. Specifically, the detergents were found to cause damage at a dilution factor of 1:20,000, but not at a dilution factor of 1:80,000, which is the dilution factor used to approximate detergent residue on dishes washed in a standard household dishwasher.
Notably, the household detergents evaluated in the study did not include certain rinse aids. The researchers are now evaluating rinse aids used in home dishwashers and are finding that the products containing alcohol ethoxylates show the same toxic effects associated with the commercial rinse aids examined in this study [2].
The findings regarding household dishwashers raise at least a couple of questions in my mind. First, this study found that even very small doses of rinse aid—doses too small to cause cell death—impacted essential pathways of the exposed cells. Is that same effect observed for household detergents? In other words, even if the detergent residue does not cause cell death, does chronic exposure nonetheless disrupt the gut barrier over time?
Second, the household dishwasher detergents were found to be toxic up to a dilution of 1:20,000. The dilution ratio is calculated based on the amount of detergent added by the user and the amount of water used in the washing cycle. Would we expect to find a dilution ratio of 1:20,000 (i.e. four times the dilution factor used by the researchers to approximate a standard household dishwasher) in certain homes based on variations in the amount of detergent and/or water used? Might handwashing dishes yield detergent residue in that range?
I will be keeping an eye out for this group’s ongoing research regarding household dishwasher detergents and hope to see some of these questions answered.
So where does this leave us?
Most of us are not going to abandon dining out, altogether, in an effort to avoid commercial rinse aid or other undesirable chemicals.
But we can raise awareness on this topic. Awareness that eventually drives change.
And until then, we can start in our own homes. Let’s choose products that are made with ingredients we can feel good about. If you haven’t already, check out my roadmap for doing just that.
“Through public education and continued research, we can empower consumers to avoid specific products and minimize the epithelial barrier and microbiome damage that’s compounding due to continuous exposure.”
Sources
[1] Ismail Ogulur et al., Gut epithelial barrier damage caused by dishwasher detergents and rinse aids, 151 J. Allergy Clin. Immunol. 469 (2023).
[2] Cezmi A. Akdis, Scrubbing away our collective health, Boston Globe (March 8, 2023, 3:00 AM), https://www.bostonglobe.com/2023/03/08/opinion/scrubbing-away-our-collective-health.
[3] Reimagining “Clean”—Our Collaboration with Dr. Cezmi Akdis and SIAF, Cultured-Seed, https://seed.com/cultured/reimagining-clean.
[4] Media Release, Universitat Zurich, Commercial Dishwashers Destroy Protective Layer in Gut (Dec. 1, 2022), https://mb.cision.com/Main/22033/3675630/1706223.pdf.
