The anti-inflammatory effects of three different dietary supplement interventions

Background: Understanding how diet influences inflammation requires identifying specific dietary components responsible for anti-inflammatory effects. This study examined the impact of six-week supplementation with a single-source prebiotic fibre (inulin), omega-3, or a synbiotic (fermented kefir + prebiotic fibre mix) on a broad range of inflammatory markers. Methods: Serum inflammatory proteins were profiled using the Olink 96 inflammation panel in a 6-week intervention. Participants received one of the following: synbiotic (n = 20; 170 ml kefir + 10 g prebiotic), omega 3 (n = 33; 500 mg/day), inulin fibre (n = 31; 20 g/day), or no supplementation (n = 20 control). Changes from baseline and between groups were analysed using parametric methods and effect sizes (Cohen’s d). FDR-adjusted p < 0.05 was considered significant. Results: All three dietary interventions significantly reduced inflammatory markers versus control. TNF-α decreased with omega-3 (d= − 0.618, 95% CI -0.73 to -0.09, p = 0.01) and inulin fibre (d=–1.012, 95% CI -0.71 to -0.20, p = 0.001). The synbiotic group showed broader and larger reductions, including IL-6 (d=–0.882,95% CI -1.36 to -0.17, p = 0.01), IFN-γ (d=–0.940, 95% CI -2.03 to -0.31, p = 0.009), SIRT2 (d=–1.505, 95% CI -1.30 to -0.51, p < 0.0001), 4EBP1 (d=–1.384, 95% CI -1.43 to -0.32, p = 0.0004), CCL23 (d=–1.356, 95% CI -1.40 to -0.48, p = 0.0002), and mucosal cytokines CCL25 (d=–1.137, 95% CI -0.90 to -0.23, p = 0.001) and CCL28 (d=–1.006, 95% CI -0.80 to -0.16, p = 0.003). Increases in serum butyrate correlated with reductions in IL-6 following the synbiotic intervention. Conclusions: All interventions reduced systemic inflammation, but the synbiotic produced broader and stronger effects, targeting proteins linked to immune and metabolic function. While gut microbiome profiling was not included in this study, it is planned in future work to clarify how synbiotics may influence host–microbiome interactions and inflammatory regulation. Trial registration: Trial registration Clinicaltrials.gov NCT06480812. Registered 28th June 2024 Retrospectively registered https//clinicaltrials.gov/study/NCT06480812.