SAPP Defines “Gut Health”: Nature Reviews Gastro & Hepatol | Feb. 2026

“Gut health” is widely used by clinicians, researchers, industry, and the public—but until now lacked a unified, clinically usable definition. This ISAPP consensus statement convened an interdisciplinary expert panel to clarify what “gut health” should mean and how it should be measured, particularly in the context of diet, fermented foods, probiotics, prebiotics, and microbiome research.

The panel proposes a pragmatic definition: gut health is “a state of normal gastrointestinal function without active gastrointestinal disease and gut-related symptoms that affect quality of life.” Crucially, the definition is not limited to absence of diagnosis: a patient with IBD or coeliac disease may still have gut health during remission. Equally, poor gut health can exist without obvious symptoms or without measurable abnormalities—highlighting the gap between patient experience and current objective testing.

The statement emphasizes that gut health is multidimensional, spanning functional physiology (motility, secretion, absorption), microbiome-related functions, barrier integrity, immune homeostasis, gut endocrine function, and the gut–brain axis. The authors also review clinically accessible metrics and caution that many emerging “gut health tests” lack validated normal ranges or correlate poorly with meaningful outcomes.

This consensus provides a needed foundation for consistent clinical communication and for designing dietary/biotic intervention trials with clearer endpoints and more defensible claims.

20 Key Takeaways

Gut health needed a standard definition—the term has been used inconsistently across science, medicine, and marketing.

ISAPP defines gut health as normal GI function without active GI disease and symptoms that impair quality of life.

Disease diagnosis ≠ absence of gut health: remission states (e.g., IBD in remission) can meet gut health criteria.

Conversely, poor gut health can exist without symptoms (subclinical dysfunction) or without measurable abnormalities.

The framework integrates subjective experience + objective function—both matter.

The concept applies to the entire GI tract, from mouth to anus.

“Gut health” is considered broadly synonymous with gastrointestinal health, and includes digestive health.

Transient symptoms from normal physiology (stress diarrhea, travel constipation) should be distinguished from persistent QOL-impacting symptoms.

Quality of life impact is central—symptoms become “clinically important” when they are bothersome and impair daily living.

The statement organizes gut health into six functional domains: digestion/physiology, microbiome, barrier, immunity, endocrine, gut–brain axis.

Many objective measures (e.g., permeability tests, microbiome indices) lack validated normal ranges and have variable reproducibility.

Microbiome testing currently cannot define an individual’s gut health reliably in clinical practice.

“Dysbiosis” is a problematic term—microbiome patterns vary widely by geography, age, and context.

Barrier function (“leaky gut”) is often overinterpreted; all guts are selectively permeable, and many claims exceed evidence.

Stool tools like Bristol stool form scale and symptom frequency/duration remain highly practical clinical metrics.

Inflammation assessment is best supported by histology when needed; noninvasive markers (CRP, fecal calprotectin) are helpful but not definitive.

Diet is a major determinant, but responses are highly individualized; “one diet fits all” is unsupported.

Research outcomes labeled “gut health” are often heterogeneous—this consensus encourages clarity about which domain is being targeted.

The panel argues for development of core outcome sets to standardize gut health research and reduce reporting bias.

This document is a starting point: future work must refine validated biomarkers, normal ranges, and determinants of future gut health risk.