Zonulin: What assay is used in the Microbiome Explorer Comprehensive panel to measure stool zonulin, and has it been specifically validated to detect true zonulin (as opposed to zonulin-related proteins or pre-haptoglobin-2)?

The zonulin assay detects related peptides rather than true zonulin.
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- The ELISA used detects zonulin family peptides (ZFPs), which are structurally similar to zonulin (pre-haptoglobin-2) but not identical.
- Studies confirm the assay does not detect true zonulin (pre-haptoglobin-2).
- Elevated ZFPs have been associated with health conditions linked to gut barrier changes, but their biological significance is still unclear.
- The assay is CE-certified, but neither serum nor stool ZFPs are validated as stand-alone measures of intestinal permeability.
- Currently, no stool assays specifically validated for pre-haptoglobin-2 exist, though the field is being monitored for new developments.
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10.3389/fendo.2018.00022

https://doi.org/10.1136/gutjnl-2020-323026