Toxic soap left on restaurant dishes can harm gut barrier

Beware of eating out! Industrial restaurant dishwashers leave toxic soap residue on cutlery and crockery that may cause allergies, inflammation and DEPRESSION, researchers warn

  • Commercial dishwashers use toxic rinse aid to clean plates in 60-second cycles
  • In many restaurants, a chemical residue is left behind on customers’ crockery
  • The detergent substances can break down the protective barrier in the gut 

Industrial restaurant dishwashers leave toxic soap residue on plates, a study has found.

Researchers from the University of Zurich in Switzerland say that even in low doses, alcohol ethoxylates — a chemical in the rinse agent — could harm the barrier in the gut.

The chemical is also present in household dishwasher detergent, but not at concentrations high enough to do any damage.

Industrial dishwashers have such short cycles that residue is left on the plates.

The resulting weakening of the gut barrier is linked to a host of health issues. 

Experts suggested it means serial restaurant-goers could be at risk of allergies, inflammation and depression.

Plates in restaurants are being cleaned, but the substance used to sterilize them is not being washed off properly. The substance can harm the gut barrier if ingested, researchers found

What a leaky gut barrier can lead to: 

Toxic substances, such as those the researchers found in dishwasher detergent, can harm the barrier in the gut.

This barrier determines what chemicals enter the body.

If toxic substances are let through, the researchers ‘assume’ this could put people at a higher risk of: 

Food allergies, gastritis, diabetes, obesity, cirrhosis of the liver, rheumatoid arthritis, multiple sclerosis, autism spectrum disorders, chronic depression and Alzheimer’s disease.

Lead study author Cezmi Akdis, a professor of experimental allergology and immunology at Zurich , said: ‘We assume that defective epithelial barriers play a role in triggering the onset of two billion chronic illnesses.’

Speed is of the essence in restaurants, meaning cutlery and crockery need to be cleaned as quickly as possible so they can be used for the next round of customers.

Commercial dishwashers normally run two 60-second cycles — one circulating hot water and detergent and the second circulating water and rinse aid.

It is this rinse aid that could cause havoc in the gut, as traces remain on plates when the food is served to customers.

Dr Akdis said: ‘What’s especially alarming is that in many appliances, there’s no additional wash cycle to remove the remaining rinse aid.’

The researchers wanted to find out what this residue would do to the epithelial barrier in the gut — the layer of cells that lines the intestinal tract and controls what enters the body.

The researchers tested the dishwasher substance on artificially grown human cells resembling organs and intestine cells on microchips.

They diluted the rinse aid to be in line with the amounts that would be left behind on a dry plate.

In high doses, the rinse agents destroyed the intestinal epithelial barrier cells, and in lower doses, made them more leaky.

Damage to the barrier is associated with a whole host of conditions including food allergies, gastritis, diabetes, obesity, cirrhosis of the liver, rheumatoid arthritis, multiple sclerosis, autism spectrum disorders, chronic depression and Alzheimer’s disease. 

The study, published in the journal Allergy and Clinical Immunology, also found the washing substance activated genes and proteins that could promote inflammatory responses.

This reaction was due a specific component of the rinse aid — alcohol ethoxylates. 

The researchers noted that dish-cleaning protocols in restaurants have serious implications to public health.

Dr Akdis said: ‘The effect that we found could mark the beginning of the destruction of the gut’s epithelial layer and trigger the onset of many chronic diseases.

‘It is important to inform the public about this risk, since alcohol ethoxylates seem to be commonly used in commercial dishwashers.’

Normal dishwashers and household rinse agents will contain traces of alcohol ethoxylates, but the dishwasher cycle will reduce to concentration to a safe amount.