• autoimmune disease
• celiac disease
• epithelial barrier
• epithelial permeability
• gut inflammation

I read with great interest the commentary by Massier et al 1 to the paper published in GUT by Talley et al 2 on their report suggesting that zonulin is not a good gut permeability biomarker for irritable bowel disease, functional dyspepsia and non-coeliac gluten sensitivity. While I appreciate the authors’ effort in making the point of the poor reliability of the commercially available ELISA in measuring zonulin, I think that some issues need to be clarified to avoid misleading the readership and, therefore, add more confusion to a field that would strongly benefit from greater clarity on this topic. Having been responsible for the discovery of zonulin and for the development of the first ‘in house’ ELISA for measuring zonulin, I think I am well positioned to provide the following clarifying points