Anthocyanins and Reduced Hemoglobin A1c

Across all 3 studies in the database, anthocyanins consistently show beneficial effects on reducing hemoglobin A1c, with moderate effect sizes reported in the highest-quality evidence. A meta-analysis of 32 RCTs (1491 participants) found a statistically significant moderate reduction (SMD: -0.65; 95% CI: -1.00 to -0.29), and a systematic review reported modest reductions of ~0.3-0.5% HbA1c at doses up to 320 mg/day. The evidence predominantly comes from mixed populations (healthy and cardiometabolic disease).

• Effective dose range: up to 320 mg/day
• Studied populations: mixed (healthy populations and those with cardiometabolic diseases)

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed).