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What does the intestinal barrier consist of and why it is important to maintain balance in it.


What does the intestinal barrier consist of and why it is important to maintain balance in it.

by | 6 of May of 2024 | Nutrition, Health

Our health is largely determined by the intestinal barrier. This is an interaction between the outside and the internal environment of our body. In the following article we detail what this barrier consists of, why it is important to maintain a balance in it and what role intestinal permeability plays in its functionality and the dietary factors involved in it.

What is intestinal permeability?

Intestinal permeability refers to the ability of the small intestine to regulate the passage of substances between the small intestine. While it allows the passage of nutrients, it prevents the passage of pathogens and toxins.

When permeability is increased, certain harmful substances can enter the bloodstream and cause health problems. Stress, alcohol consumption, a Western dietary pattern or exposure to toxic substances are factors that can lead to such excessive permeability.

In the past, the term gut flora was used to refer to the set of bacteria that formed this barrier. However, because it is not only bacteria but a multitude of micro-organisms that form part of it, it is now known as the gut microbiota. And it plays such an important role in health because it is able to regulate the protective function of the intestinal mucosa, as well as the immune system.

Selective gut permeability, key to health

A healthy gut is characterised by selective intestinal permeability for nutrients, water and bacterial products. This is due to the connections between the intestinal cells, which are sealed together. This enables the absorption of nutrients and prevents harmful substances from passing through the intestinal epithelium into the blood.

Consequences of impaired intestinal permeability

Hippocrates already said that “all disease begins in the intestine”. Altered intestinal permeability has been associated over the last decade with several chronic conditions, including diseases originating in the gastrointestinal tract such as inflammatory bowel disease, coeliac disease, irritable bowel syndrome, but also diseases such as Alzheimer’s, Parkinson’s, type 2 diabetes, obesity, autism spectrum disorders and depression.

It is important to note that, although we associate the above diseases with increased intestinal permeability, this does not mean that permeability is the cause, rather, it could be the consequence. Therefore, we cannot establish causality, but rather the association between them.

How does diet influence intestinal permeability?

Consumption of a Western dietary pattern is associated with an increased risk of developing inflammatory bowel disease (IBD), a condition characterised by altered intestinal permeability.

The Western diet, characterised by a high intake of refined sugars and oils, alcohol, a high intake of saturated fats, an imbalance in the intake of omega-3 and 6 fatty acids, consumption of processed meats, refined grains, excess salt and fried foods, coupled with a low intake of fruits, vegetables, whole grains, fish, nuts and seeds.

The constant caloric excess caused by following a Western diet promotes multiple chronic diseases: hyperinsulinaemia, insulin resistance, dyslipidaemia, overstimulation of the sympathetic nervous system, low-grade systemic inflammation, dysbiosis, endotoxaemia, increased production of reactive oxygen species and oxidative stress.

The Western diet, by altering the gut microbiota, causes dysfunction of the intestinal barrier, increasing intestinal permeability and the entry of toxic metabolites into the circulation. Contributing to the development of chronic low-grade inflammation.

Biomarkers of intestinal permeability

The diagnosis of altered intestinal permeability can be assessed by different biomarkers in the blood:

  • Zonulin (elevated levels reflect hyperpermeability).
  • Fatty acid binding proteins (related to intestinal epithelial damage). It has also been identified as a diagnostic marker for necrotising enterocolitis).
  • Citrulline (a marker of reduced enterocyte mass, negatively correlated with the severity of intestinal disease such as coeliac disease and Crohn’s disease).
  • Glucagon-like peptide (reduced GLP-2 may indicate impaired intestinal barrier function).
  • Serum levels of the endotoxin LPS have been implicated as a potential marker of increased intestinal permeability, more specifically as a marker of bacterial translocation.


Impaired intestinal permeability can be a major health problem. Maintaining good lifestyle habits, being active, following a healthy diet, and trying to reduce chronic stress are important measures to prevent intestinal permeability, including the abuse of drugs and antibiotics. Once diagnosed, it can be treated through different nutritional and dietary measures, among others, always with the help of a professional. It is complex.

Bibliographical references

These are the bibliographical references that we have used to prepare this article: