What is intestinal permeability (“leaky gut”)?

Under healthy conditions, the intestinal mucosa permits the absorption of vital nutrients from the gut lumen while presenting a barrier against the passage of pathogenic substances into the body.

What is Intestinal Permeability?

Mucosal surfaces are lined by epithelial cells. These cells establish a barrier between sometimes hostile external environments and the internal milieu. However, mucosae are also responsible for nutrient absorption and waste secretion, which require a selectively permeable barrier.

These functions place the mucosal epithelium at the centre of interactions between the mucosal immune system and luminal contents, including dietary antigens and microbial products. Together with the gut-associated lymphoid tissue (GALT) and the neuroendocrine network, the intestinal epithelial barrier, with its intercellular tight junctions, controls the equilibrium between tolerance and immunity to non-self antigens.

The Effect of Intestinal Permeability

Zonulin is the only physiological modulator of intercellular tight junctions described so far that is involved in trafficking of macromolecules and, therefore, in tolerance/immune response balance. When the finely tuned zonulin pathway is deregulated in genetically susceptible individuals, both intestinal and extraintestinal autoimmune, inflammatory, and neoplastic disorders can occur.

This new paradigm subverts traditional theories underlying the development of these diseases and suggests that these processes can be arrested if the interplay between genes and environmental triggers is prevented by reestablishing intestinal barrier function.

A variety of food substances affect the key transporter activities, impacting on tight junction permeability, metabolic enzyme expression, immune functions and so on – including, but certainly not limited to, gluten, casein and corn. Modulation of the intestinal functions by dietary substances is therefore essential to promote health and recovery.

Testing for intestinal permeability
  • Intestinal permeability and absorption test
  • Comprehensive stool analysis including parasitology CDSA
  • Food sensitivity testing

In clinical practice I have found the greatest value in carrying out a CDSA. Increased levels of pathogenic microbes as well as inflammation and low levels of sIgA increase the risk of intestinal permeability. If a client has an autoimmune condition as well as significant gut dysbiosis, it is essential to address the microbiome and the gut wall in order to address the immune system.