Does Dishwasher Rinse Aid Damage the Gut Epithelial Barrier?
I took a deeper look into the 2022 study that has spawned countless fear-mongering videos across the internet.
Does dishwasher rinse aid damage the gut epithelial barrier?
First of all, what is the gut epithelial barrier?
In simple terms, it’s the lining of the human digestive tract.
Rinse aid is a dishwashing product that gets dispensed in very small quantities during the rinse portion at the end of a dishwashing cycle. It’s a surfactant that reduces the surface tension of the water, allowing it to slide off of dishes rather than sticking to them. In short, rinse aid helps dishes dry faster and prevents water spots or streaks after drying.
One of the recent concerns with rinse aid is whether any of it is left behind on dishes after being run through the dishwasher, and if so, whether ingesting even small amounts of it may be harmful to the human body.
In December 2022, a research study ominously titled, “Gut epithelial barrier damage caused by dishwasher detergents and rinse aids” was published online, and in February 2023 was published in the Journal of Allergy and Clinical Immunology. The purpose of the study was to determine the effects of rinse aid on human gut health.
Since its publication, this study has been frequently cited all over the internet—including in the comment sections of nearly every video I’ve made about rinse aid—as proof that dishwasher rinse aids are “toxic to gut health,” and therefore should not be used.
This prompted me to look further into it.
First, I looked through the 2022 study to see what it actually said. Upon doing so, I discovered a few important parts of the study that the people who frequently cite it have either missed or ignored. Most notably, only commercial/professional dishwashers, detergents, and rinse aids (not household/residential) were found to exhibit higher levels of cytotoxicity (the quality of being toxic and damaging to cells).
Only commercial/professional dishwashers, detergents, and rinse aids (not household/residential) were found to exhibit higher levels of cytotoxicity
The study mentions that commercial/professional dishwashers are those that are used “in public food consumption areas including restaurants, schools, military barracks, and hotels,” and suggests that the effect on the gut barrier is a result of the higher concentration of alcohol ethoxylates in commercial rinse aids. The study mentions that professional dishwashers were noted to have left “the remnant of a significant amount of cytotoxic and epithelial barrier-damaging rinse aid remaining on washed and ready-to-use dishware,” which is the biggest concern for method of ingestion.
As for household dishwashers, the results of the study did not mention whether household dishwashers leave the same amount of residue, but it is heavily implied that professional dishwashers are the main culprit.
Regarding household detergents and rinse aids and their concentration of alcohol ethoxylates, the study states, “a 1:80,000 dilution is generally used in a household dishwashing[sic]. [...] The 3 household dishwasher detergents [tested in this study] did not elicit any cytotoxicity on Caco-2 cells at 1:80,000 dilution.”
“a 1:80,000 dilution is generally used in a household dishwashing[sic]. The 3 household dishwasher detergents [tested in this study] did not elicit any cytotoxicity on Caco-2 cells at 1:80,000 dilution.”
- 2022 Study
In simpler terms, the study found that household dishwashers, detergents, and rinse aids do not pose harm to gut health, assuming they are being used correctly.
Everything in moderation, after all.
The 2022 study concluded that gut cells were negatively affected “by rinse aid in concentrations used in professional dishwashers” and that “the alcohol ethoxylates present in the rinse aid were identified as the culprit component causing the epithelial inflammation and barrier damage.”
So, does that mean commercial rinse aid is toxic to gut health? Not quite.
In an article titled, “Science vs. Sensation – Dishwasher Detergent Safety,” published by Michigan State University’s Center for Research on Ingredient Safety in 2024, the authors dug a little deeper into the claims made by the 2022 study.
Regarding the claim that commercial rinse aids cause increased gut inflammation, the 2024 article says, “For inflammation to occur, immune cells must be present in the body. Without immune cells, there is no inflammation. The study has no immune cells, meaning claims about inflammation are unsubstantiated.”
And regarding the claim that commercial rinse aids cause increased gut permeability (also known as “leaky gut”), the article says, “The dilution ratios presented in the paper are significantly higher than any concentration we’d be exposed to when using products as designed and directed in a home setting. For example, the dilution ratio in one experiment was more than 300 times more concentrated than what we’d be exposed to in a typical use setting. Even the highest dilution factor they explored was 2 times more concentrated than a typical use case.”
According to the results of the 2022 study, for rinse aid to be cytotoxic–even in a professional dishwasher–the residue remaining on the dishes at the end of a cleaning cycle would have to be at least two times as much as what is considered seen in “typical use”. But regarding that supposed cytotoxicity, the 2024 MSU article goes on to say that the authors of the 2022 study, “used colorectal cancer cells to represent healthy gut epithelial cells. While this may be an appropriate cell choice for some models, it does not accurately mimic healthy intestinal tissue. The paper’s conclusions do not mimic human biology or human exposure, meaning the conclusions are not relevant to our day-to-day lives.”
“The paper’s conclusions do not mimic human biology or human exposure, meaning the conclusions are not relevant to our day-to-day lives.”
- “Science vs. Sensation — Dishwasher Detergent Safety,” 2024
While looking into this study myself, I found an additional factor that may have affected the results—all of their research was performed using only one model of professional dishwasher (the GS501 by German brand Winterhalter) and one model of household dishwasher (the GS60AV by German brand AEG, whose parent company is Swedish manufacturer Electrolux).
The problem with only using one type of dishwasher for each category is not all dishwashers function the same—cycle times can vary from brand to brand, or even from model to model within the same brand. The study suggests that all commercial/professional dishwashers leave behind levels of residue that can be cytotoxic, however, you cannot make that claim if you’ve only studied these effects using one model of dishwasher.
While the 2022 study found that alcohol ethoxylates–an ingredient found in rinse aid–can be cytotoxic, it cannot make the broader claim that dishwashers leave behind enough residue for dishwasher rinse aid to be harmful to gut health without further research.
Sources:
1. 2022 Study (original e-publication): https://pubmed.ncbi.nlm.nih.gov/36464527/
2022 Study (publication in the Journal of Allergy and Clinical Immunology): https://www.jacionline.org/article/S0091-6749(22)01477-4/fulltext
2024 MSU Article: https://cris.msu.edu/news/featured/science-vs-sensation-dishwasher-detergent-safety/
American Cleaning Institute page on “Dishwasher Detergent and Rinse Aid Safety”: https://www.cleaninginstitute.org/dishwasher-detergent-and-rinse-aid-safety
2025 New York Times Wirecutter article “Does Dishwasher Rinse Aid Really Harm Your Gut? Our Expert Weighs In.”: https://www.nytimes.com/wirecutter/reviews/advice-dishwasher-rinse-aid-safety/