Background: Several studies have shown effects of anthocyanin on blood pressure, blood glucose, and lipid profile in different conditions, but the results of these studies are controversial. We summarized evidence from randomized clinical trials (RCTs) that investigated the effects of anthocyanin supplementation on cardio-metabolic biomarkers in adults.

Methods: The literature searches of MEDLINE and EMBASE for published studies in English was performed up to August 2017. Results were summarized as mean differences (MD) with 95% confidence intervals (CI). Effect sizes of eligible studies were pooled using random-effects models (the DerSimonian-Laird estimator). Heterogeneity among studies was evaluated by the Cochrane Q test.

Results: Of 5370 papers, 19 RCTs met inclusion criteria. There was no significant effect of anthocyanin supplementation on weight, waist circumference (WC), body mass index (BMI), systolic and diastolic blood pressure (SBP and DBP). Our results indicated that anthocyanin supplementation had no significant effects on HbA1c (MD: -0.32; 95% CI = -0.64, 0.00; p = 0.050) with no heterogeneity (I² = 0.0%, p = 0.966, no significant heterogeneity), however anthocyanin supplementation had significant effect on HOMA-IR (MD: -0.21; 95% CI = -0.36, -0.07; p = 0.004) (I² = 37.9%, p = 0.200, no significant heterogeneity) in adults. Intake of anthocyanin had no significant effects on FBS (MD: 0.25; 95% CI = -5.70, 6.21; p = 0.933) and serum insulin (MD: 0.09; 95% CI = -0.92, 1.11; p = 0.860) with high heterogeneity for these variables (p = 0.000, and I² = 83.5%) and (p = 0.098, and I² = 52.4%), respectively. Anthocyanin supplementation had significant effects on total cholesterol (TC) and low density lipoprotein (LDL) for more than 300 mg/day intervention for more than 12 weeks. The dose and duration of supplementation were the potential sources of heterogeneity among most of the trials.

Conclusion: The results demonstrate that supplementation with anthocyanin have beneficial effect on HOMA-IR in adults.