Epithelial Barrier Theory

Public Information

A Fresh Understanding of the Term “Harmful”

Epithelial barrier theory and the changing concept of chronic microtoxicity:

After the World War II and during the second Industrial Revolution, there was a significant surge in the prevalence of processed foods, cigarette smoke, and diesel emissions, coinciding with a revolutionary period in chemistry. This era also marked the commencement of our fascination with “cleanliness,” as chemical-based laundry and dishwasher detergents, household cleaning products, and even cosmetics made their debut. Since 1960, more than 350,000 new chemicals have been introduced into our environment, and a considerable number of these compounds remain undisclosed to the public. Approximately 50,000 are classified as confidential, while around 70,000 are described ambiguously.

As an immunologist with over four decades of experience in researching immune regulation mechanisms in conditions such as allergy, asthma, autoimmune diseases, and other chronic ailments, our team has come to recognize that the introduction of these chemicals has not been without consequences. These substances have played a crucial role in the global and epidemic-like increase in chronic health conditions over the past 65 years.

Our Modern Lifestyle and Development and Exacerbation of Disease

The human body possesses protective cellular layers known as epithelial barriers that line the skin, respiratory tract, and digestive system. These intact epithelial barriers play a vital role in maintaining a state of equilibrium, as they shield the body’s tissues from infections, environmental toxins, pollutants, and allergens.

However, numerous chemical substances commonly present in everyday consumer products, ranging from toothpaste and shampoo to detergents and processed foods, have a known propensity to harm these crucial barriers, rendering them less effective and increasing their permeability. When these barriers become compromised or ‘leaky,’ foreign substances and microorganisms can breach them, infiltrating tissues where they don’t belong. Once these intruders enter the bloodstream, they can incite an inflammatory immune response, potentially triggering or exacerbating a variety of chronic inflammatory diseases.

These chronic diseases, which include conditions like asthma, inflammatory bowel disease, diabetes, rheumatoid arthritis, and chronic depression, are more prevalent in industrialized nations. Moreover, their incidence continues to climb in developing countries in tandem with the processes of urbanization and industrialization.

Our research journey into the realm of epithelial barriers commenced in the early 2000s when we first recognized the role of damaged barriers in the development of several diseases. These diseases were correlated with a decrease in microbial diversity and localized tissue inflammation. Over the course of two decades and the publication of more than 60 scientific papers, my team and I formulated the Epithelial Barrier Theory. This theory suggests that the surge in substances that harm these barriers, linked to industrialization, urbanization, and modern lifestyles, is at the core of the global increase in allergic, autoimmune, and chronic conditions. These conditions now affect over a billion people worldwide.

The ongoing discussion surrounding society’s burden of toxic exposures is not a novel one. Phrases such as ‘clean,’ ‘natural,’ and ‘non-toxic’ have gained popularity on product labels. Nevertheless, until recently, we have lacked the technological tools and methodologies needed to establish a clear threshold for the toxicity of everyday products when viewed through the lenses of the microbiome and epithelial immunology. This knowledge gap has led to excessive exposure to potentially harmful substances, to the detriment of our collective health.

The Toxic Burden of Everyday Items

Consider, for instance, the rinse aid used in the dishwashing process, a common component in restaurants, coffee shops, hotels, and bars worldwide.

Our recent investigation focused on the effects of dishwashing detergents and rinse aids on health, particularly their impact on gut barrier integrity. Our findings, which we recently published convey an urgent message: Commercial rinse aid disrupts the protective layer within the gastrointestinal tract.

To be more specific, our research revealed that a chemical compound commonly found in commercial rinse aids leaves behind residue on cleaned dishes, even after undergoing a standard rinse cycle. Remarkably, even the tiniest traces of this compound has the ability to harm cells and compromise the epithelial barrier in unsuspecting diners. Another study conducted by my team showed that laundry detergents and rinse residues produce similar damaging effects in the respiratory tract. It’s worth noting that the widespread use of synthetic detergents coincided with the increase in allergic diseases starting around 1950.

These studies are just a couple of examples among many that underscore the necessity of conducting further assessments on these compounds and their potential impact on our well-being

Revisiting the Notion of Toxicity for a New Definition of Clean

What practical steps can we take to safeguard our well-being? While it may be unrealistic to expect people to cease washing their clothes or dining out, raising public awareness can serve as the cornerstone for initiating change.

Individually, all of us are part of modern society, and it is likely that our protective barriers have been compromised to some extent. However, by promoting public education and conducting ongoing research, we can empower consumers to make informed choices, avoid specific products, and reduce the cumulative damage to epithelial barriers and the microbiome resulting from continuous exposure. A collaborative effort involving various stakeholders, including regulatory bodies, product manufacturers, retailers, distributors, and scientists from diverse fields, is urgently required.

As a crucial initial step, we must acknowledge that our existing toxicity criteria are outdated in light of advancements in science and technology. It is imperative that we redefine the concept of “toxicity” and seek out safer alternatives to the barrier-disrupting agents currently in use.

At the Swiss Institute of Allergy and Asthma Research, in partnership with Seed Health, a microbiome science company, my team has recently introduced an innovative immunology platform. This platform is designed to assess the toxicity and pro-inflammatory effects of over 200 commonly utilized chemicals while identifying compounds that could potentially safeguard or restore these vital barriers and the microbiome. This research has the potential to drive the development of the next generation of home and personal care products, transforming them into tools for preserving—or even enhancing—our immunological health.

Paracelsus, often regarded as the father of toxicology, stated in 1493, ‘sola dosis facit venenum’ –– meaning that the dose determines the poison. All substances can have toxic potential; it hinges on the quantity. Just as green technology is essential for addressing the pressing environmental challenges posed by climate change, I am committed to the development of technologies that can promote the ‘deindustrialization’ of our bodies. I am calling for a collective effort towards research, public education, regulation, and innovation.

The future of our health hinges on these actions.

Cezmi A. Akdis, MD, is the director of the Swiss Institute of Allergy and Asthma Research in Davos.