Leaky gut, or increased intestinal permeability, is a complex physiological state that has generated significant interest across clinical and research communities. Diagnosing it remains challenging because there is no single universally accepted clinical gold standard. Rather than relying on symptoms alone, a combination of functional tests, biomarker assays, and microbial profiling can help form a clearer picture. One useful resource summarizing this approach is [Can the test detect leaky gut syndrome?](https://www.innerbuddies.com/blogs/gut-health/test-detect-leaky-gut-syndrome). Microbiome analysis is emerging as a complementary tool for assessing factors that contribute to barrier dysfunction. By sequencing stool samples, clinicians and researchers can quantify beneficial species (for example, Faecalibacterium prausnitzii or Akkermansia muciniphila) and identify overgrowth of pro-inflammatory taxa. These microbial signatures relate to functions such as short-chain fatty acid production, mucin maintenance, and lipopolysaccharide (LPS) load — all of which influence tight junction regulation and immune activation. A microbiome report should be interpreted alongside targeted biomarkers. Tests like the lactulose/mannitol permeability assay measure sugar absorption ratios to infer transepithelial leakiness, while fecal or serum assays for zonulin, calprotectin, and secretory IgA offer biochemical context. Microbiome results add mechanistic insight: a low butyrate-producing capacity, for instance, helps explain why epithelial repair may be impaired even if a single permeability assay is borderline. It is also helpful to view microbiome data within a practical framework: dietary patterns, medication history (especially antibiotics or NSAIDs), stress, and comorbid conditions all shape microbial ecology and barrier resilience. For evidence-based guidance on supportive dietary approaches that align with microbial restoration, see A Gut Health Diet That Actually Works. For readers seeking background on protective microbes that support mucosal defenses, the role of beneficial taxa is reviewed at Beneficial Bacteria: Your Gut’s Natural Defenders. Additional practical summaries are available in overview articles such as A Gut Health Diet That Actually Works on the Telegraph platform. Limitations and interpretation caveats are important. Zonulin assays can vary in specificity, and some commercially available tests detect related proteins or precursors. Microbiome testing does not measure permeability directly; instead, it identifies patterns and potential mechanistic drivers that, when combined with symptom profiling and biochemical assays, strengthen diagnostic confidence. In summary, microbiome testing is a valuable, non-invasive component of a multi-modal evaluation for suspected increased intestinal permeability. It supplies actionable information about microbial contributors and metabolic capacity that help explain biomarker findings and guide targeted, individualized interventions. For those exploring testing options, product details and methodology are often provided by testing platforms (for example, product information), which can clarify what specific metrics are reported.