Advances in Research

Cardiovascular disease (CVD) remains the leading cause of death and disability worldwide, and dietary modulation of the gut microbiota has emerged as a candidate strategy for risk reduction. Prebiotics—substrates selectively utilised by host microorganisms to confer a health benefit—have been proposed to influence cardiovascular risk through short-chain fatty acid (SCFA) production, modulation of trimethylamine-N-oxide (TMAO) generation, lipid-lowering effects and attenuation of low-grade inflammation. This critical narrative review synthesises mechanistic, observational and randomised controlled trial (RCT) evidence published up to 6 April 2026 concerning inulin-type fructans, β-glucans, galacto-oligosaccharides and related fermentable fibres in relation to lipid profile, blood pressure, glycaemic control, inflammatory biomarkers and clinical cardiovascular outcomes. Evidence for cholesterol-lowering effects, particularly from viscous fibres such as oat β-glucan, is comparatively consistent, with meta-analyses reporting modest but reproducible reductions in low-density lipoprotein cholesterol. Evidence for blood pressure reduction is more heterogeneous, with meaningful effects observed predominantly in hypertensive populations and largely derived from animal models rather than adequately powered human trials. Mechanistic work implicates SCFA-receptor signalling (GPR41, GPR43, GPR109A) in vascular and renal blood pressure regulation, while the relationship between prebiotic fibre intake and TMAO remains inconsistent, with a small pilot trial suggesting attenuation only in subgroups with lower habitual meat intake. Anti-inflammatory effects are plausible but are confounded across the literature by co-administration with probiotics and by short trial durations. Methodological limitations pervade this evidence base, including small sample sizes, heterogeneous prebiotic formulations and doses, short follow-up, reliance on surrogate rather than hard cardiovascular endpoints, and frequent conflation of prebiotic, probiotic and synbiotic interventions. No adequately powered trial has examined prebiotic supplementation against incident myocardial infarction, stroke or cardiovascular mortality. This review concludes that prebiotic fibres represent a biologically plausible but incompletely validated adjunctive strategy for cardiovascular risk modification, with the strongest evidence supporting lipid-related benefits and the weakest evidence supporting hard clinical outcomes. Priorities for future research include adequately powered, long-duration trials with cardiovascular endpoints, standardisation of prebiotic dosing and characterisation, and mechanistic studies disentangling prebiotic-specific from probiotic-associated effects.