SynthesisBMC nutrition2026
Impact of probiotic supplementation on cortisol levels; GRADE-based dose-response meta-analysis.
Synthesis in BMC nutrition, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
9 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundDysregulated cortisol levels, driven by hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, are linked to stress-related disorders, including anxiety, depression, and metabolic syndromes. Probiotics, through their modulation of the gut-brain axis, may reduce cortisol levels, but evidence remains inconsistent due to study heterogeneity. Therefore, this systematic review and meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the effect of probiotic supplementation on serum cortisol levels in adults.
methodsFollowing PRISMA guidelines, we searched PubMed, Scopus, Web of Science, Embase, and Cochrane databases up to February 20, 2026. Eligible RCTs involved adult participants receiving oral probiotics compared to placebo or no intervention, with serum cortisol as an outcome. A random-effects model calculated weighted mean differences (WMDs), with subgroup and dose-response analyses to explore heterogeneity. Risk of bias was assessed using Cochrane RoB 2, and evidence quality via GRADE.
resultsFrom 41 RCTs (n = 24–214 participants), probiotics significantly reduced cortisol levels (WMD: -0.35 µg/dL, 95% CI: -0.42 to -0.27, P < 0.001), with high heterogeneity (I² = 96.9%, 95% CI: 96.1% to 97.5%). Single-strain probiotics were more effective than multi-strain. No significant dose-response relationships or publication bias were found. Evidence quality was very low due to heterogeneity and bias risks.
conclusionAlthough probiotic supplementation, particularly single-strain formulations, was associated with a modest reduction in serum cortisol levels, the high heterogeneity (I²=96.9%) and very low certainty of evidence (GRADE) preclude firm conclusions. These findings support the need for further large-scale, well-standardized RCTs to clarify the clinical utility of probiotics in stress management.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.