Gastroenterology · Medical Literature
Effect of Short-Term Grape Powder Supplementation in Patients with Crohn's Disease: A Pilot Study.
Abstract
Background: The overall objective of this pilot diet intervention study was to determine the effect of grape powder (GP) supplementation on gut microbiota composition and inflammatory markers in individuals with Crohn's disease (CD). Methods: Adult CD participants were recruited from the Digestive Health Institute at University Hospitals Medical Center, Cleveland. All participants were supplemented with 45 g/day of freeze-dried grape powder (equivalent to ~1.5 cups of fresh grapes) daily for 21 days. The primary outcome was the change in fecal microbiome profiles. Secondary outcomes included the absolute difference (day 21-day 0) in Harvey Bradshaw Index (HBI) score, fecal myeloperoxidase (MPO), and high-sensitivity C-reactive protein (hsCRP). Results: A total of 21 CD participants were included in the final analysis. After 21 days of GP supplementation, more than half of the participants (13, 61.9%) experienced a reduction in fecal MPO, while 80% (17) experienced either a reduction or no change in HBI score. Microbiome analysis revealed modest but directional shifts, including enrichment of Akkermansiaceae, Bacteroidaceae, Tannerellaceae, Rikenellaceae, and Monoglobaceae. While overall community structure did not significantly change at the cohort level, individualized microbiome responses as well as functional pathway shifts were observed following the intervention. Conclusions: Daily supplementation with freeze-dried grape powder for 21 days was safe and well-tolerated in adults with CD and was associated with modest shifts in gut microbiome composition. This study was registered on clinicaltrials.gov (NCT05972694; 5 February 2024).
Clinical relevance
Does 21 days of daily freeze-dried grape powder (45 g/day) supplementation alter gut microbiota composition and reduce inflammatory markers in adults with Crohn's disease? __SNAPSHOT__ {"studyDesign":"Single-arm, open-label pilot dietary intervention study","setting":"Digestive Health Institute, University Hospitals Medical Center, Cleveland, Ohio, USA; single academic center","sampleSize":"n=21 (final analysis); no comparator arm","population":"Adult patients with established Crohn's disease; additional inclusion/exclusion criteria not reported in available abstract","intervention":"45 g/day of freeze-dried grape powder (equivalent to approximately 1.5 cups of fresh grapes) for 21 days","comparator":"Not applicable — single-arm study with no control or placebo group","primaryOutcome":"Change in fecal microbiome profiles from day 0 to day 21","followUp":"21 days","fundingSource":"Not reported in available abstract"}
Key findings
Among 21 CD participants completing the 21-day grape powder intervention: (1) Fecal myeloperoxidase (MPO), a marker of intestinal neutrophilic inflammation, decreased in 13 of 21 participants (61.9%); no group-level absolute change, median difference, confidence interval, or p-value for MPO was reported. (2) Harvey Bradshaw Index (HBI) score — a validated clinical disease activity measure — was reduced or unchanged in 17 of 21 participants (80%); again, no absolute or relative change, standard deviation, confidence interval, or p-value was reported. (3) Microbiome analysis revealed directional shifts described as 'modest,' including relative enrichment of Akkermansiaceae, Bacteroidaceae, Tannerellaceae, Rikenellaceae, and Monoglobaceae; statistical significance of these shifts was not reported in the available abstract. (4) Data for hsCRP (a pre-specified secondary outcome) and the remaining results of the abstract are unavailable due to truncation of the provided text. NNT/NNH cannot be calculated from reported data. No adverse events were described in the available abstract excerpt.
Practice implications
This pilot study provides early, directional evidence that short-term grape powder supplementation may modestly reduce fecal neutrophilic inflammation and clinical disease activity scores in a subset of CD patients, and may promote enrichment of several bacterial families associated with mucosal health (e.g., Akkermansiaceae, which includes Akkermansia muciniphila). However, the following critical limitations prevent any practice-informing conclusions: (1) The study is single-arm with no placebo or dietary control, making it impossible to attribute observed changes to the grape powder rather than natural disease fluctuation, regression to the mean, or concurrent therapies. (2) No inferential statistics (p-values, confidence intervals, effect sizes) were reported for any outcome in the available abstract. (3) The study enrolled only 21 participants, which is insufficient to reliably estimate effect sizes or safety signals. (4) The 21-day follow-up captures no information on sustained benefit, durability of microbiome changes, or long-term safety. (5) Baseline disease severity, medication use (e.g., biologics, immunomodulators, steroids), and disease phenotype (location, behavior) are not described in the available abstract, severely limiting assessment of which patients these findings may apply to. (6) Only an abstract (itself truncated) was available for review; full-text methodology, statistical analysis, and complete results could not be evaluated. The findings cannot be generalized beyond the narrow, academic, single-center cohort studied. Grape powder supplementation should not be recommended as therapy for CD based on this data alone. __LIMITATIONS__ No control group or placebo arm — single-arm design precludes causal inference,Very small sample size (n=21) — severely underpowered for reliable effect estimation,No inferential statistics reported in the available abstract (no p-values, confidence intervals, or effect sizes for any outcome),Short follow-up duration (21 days) — insufficient to assess sustained clinical benefit or microbiome stability,Absence of data on baseline disease severity, concomitant medications, and CD phenotype limits generalizability,Open-label design introduces high risk of expectation bias in patient-reported HBI scores,Microbiome shifts described as 'modest' and 'directional' without formal statistical testing reported — hypothesis-generating only,Abstract is truncated; results for hsCRP and potentially other outcomes are unavailable for review,Single academic center in Cleveland, Ohio — limited geographic and demographic generalizability,Funding source not reported — potential conflicts of interest cannot be assessed,Surrogate endpoints (MPO, HBI, microbiome composition) were used; no endoscopic, histologic, or patient-reported quality-of-life outcomes described __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This 21-participant, single-arm, 21-day pilot found directional reductions in fecal MPO and HBI scores and modest microbiome shifts with grape powder supplementation in Crohn's disease, but the absence of a control group, inferential statistics, and adequate sample size renders these findings strictly hypothesis-generating. No change in clinical practice is warranted; adequately powered, placebo-controlled randomized trials with standardized endpoints are required before grape powder can be considered an adjunctive intervention in CD management.