Inflammatory bowel disease (IBD), including Ulcerative Colitis (UC), is a chronic gastrointestinal disorder that results in impaired quality of life and gut microbiome dysbiosis1,2. Probiotics and anthocyanins may beneficially modulate the gut microbiome and reduce inflammation. However, there is limited clinical evidence examining the separate and combined effect of these microbiome-targeted therapies in UC. This study investigated the effect of anthocyanins and multi-strain probiotic supplementation, alone and combined, on selected clinical outcomes and the gut microbiome in adults with UC.
A 12-week, four-arm, double-blind randomised controlled trial was conducted in n= 86 Australian adults with UC. Participants were allocated to: (1) anthocyanin plus placebo probiotic, (2) probiotic plus placebo anthocyanin, (3) combined anthocyanin and probiotic, or (4) double placebo. A New Zealand blackcurrant powder (NeuroberryTM) supplement provided 310mg/day anthocyanins, while the multi-strain VSL#3 probiotic was selected for its favourable evidence base regarding efficacy and safety. The primary outcome was health-related quality of life measured using the IBDQ-323. Secondary outcomes included faecal calprotectin (FCP), clinical disease activity, cognition, psychological outcomes, dietary intake, and shotgun metagenomic sequencing of faecal microbiota.
Anthocyanin supplementation significantly improved IBDQ-32 scores at 12 weeks in the intention-to-treat cohort (14.7 points, SE 7.3, p = 0.050), with greater improvements observed in participants with clinically active disease at baseline (20.6 points, SE 7.8, p = 0.015). Anthocyanin supplementation resulted in improved delayed memory recall from RAVLT 20min test (1.7 words, SE 0.8, p = 0.033). No significant changes were observed in FCP, clinical disease activity, gastrointestinal symptoms, or psychological outcomes. Gut microbiome analysis demonstrated increased a-diversity and increased prevalence of beneficial fibre-degrading, SCFA-producing bacteria including Bacteroides, Blautia, Phocaeicola, and Roseburia species in all three intervention groups. Anthocyanin interventions were additionally associated with reduced amino acid biosynthesis pathways.
Anthocyanin supplementation, administered alone or in combination with probiotics, was associated with meaningful improvements in health-related quality of life and delayed memory recall in adults with UC, with the greatest benefits observed among participants with clinically active disease at baseline. Although no significant effects were detected for clinical disease activity, faecal calprotectin, gastrointestinal symptoms or pscychological outcomes, anthocyanin supplementation led to an increase in beneficial gut bacteria. Anthocyanin supplementation was also associated with alterations in microbial metabolic pathways, suggesting potential functional changes within the gut microbiome. While no synergistic benefit of the combined probiotic and anthocyanin intervention was identified, the observed improvements in patient-reported outcomes and favourable microbiome shifts highlight the therapeutic potential of anthocyanin-rich dietary strategies as adjunctive approaches for UC management. These findings provide encouraging evidence supporting the role of anthocyanins in promoting gut health and patient wellbeing and underscore the need for larger, longer-term studies to further investigate their clinical and microbiome-mediated effects in people living with ulcerative colitis.