Zonulin is a clinically useful marker of intestinal permeability, with high levels associated with increased intestinal permeability. It is synthesized in liver and intestinal cells. Intestinal Permeability has been associated with several auto-immune, inflammatory, and neoplastic diseases, including Rheumatoid Arthritis, Asthma, IBS, IBD, eczema and food sensitivity reactions.
In a healthy GI tract, the tight junctions between cells prevent unregulated influx of luminal contents. However, certain situations, such as the presence of gluten for people with celiac disease or NCGS (non-celiac gluten sensitivity), can lead to high levels of zonulin in the GI tract. This can induce the breakdown of the tight junctions, leading to intestinal permeability and allowing zonulin to enter the bloodstream.
What’s more, zonulin is the only regulator of intestinal permeability known to be reversible, which makes it valuable in monitoring therapeutic interventions as well.