Metabolic benefits of dietary prebiotics in human subjects: a systematic review of randomised controlled trials

Adults 18+ with varied health status (healthy, overweight/obese, impaired glucose tolerance, type 2 diabetes; some trials in NASH); randomized controlled trials (including parallel-group and double-blind designs); 26 trials involving 831 participants.

Dietary prebiotic supplementation using inulin-type fructans (inulin, oligofructose, fructooligosaccharides) or galactooligosaccharides; regimens delivered via foods (e.g., prebiotic bread containing 4 g inulin per 100 g) or other forms; daily intake for periods ranging from 2 days to 24 weeks (example: 200 g/day prebiotic bread for 5 weeks delivering ~4 g inulin per 100 g).

Short-term randomized trials show dietary prebiotics can increase satiety and reduce postprandial glucose and insulin concentrations in healthy and overweight adults. Effects on energy intake, body weight, PYY, GLP-1, gastric emptying, insulin sensitivity, lipids, inflammatory markers, and immune function are inconsistent or not significant. Overall, evidence supports potential benefits for appetite regulation and postprandial glycemic control, but is insufficient to routinely recommend prebiotics for weight loss, lipid reduction, insulin sensitivity, or immune modulation. Longer, high-quality trials are needed to confirm benefits and link outcomes to gut microbiota changes.

Short trial durations and small sample sizes; heterogeneity in prebiotic type, dose, and population; some trials involved co-interventions (e.g., synbiotics or additional nutrients); reliance on surrogate endpoints and self-reported satiety; limited long-term data and gut microbiota analyses.