Effectiveness of anthocyanins rich foods on cardiometabolic factors in individuals with metabolic syndrome: a systematic review and meta-analysis

Purpose: The aim of this systematic review with meta-analysis was to determine whether anthocyanin-rich foods are effective to improve cardiometabolic markers in individuals with metabolic syndrome (MetS), compared with placebo or control interventions. Methods: We searched MEDLINE, CENTRAL, Embase, LILACS, CINAHL, and Web of Science from their inception up to March 2022. We include clinical trials (randomized clinical trials, controlled clinical trials, and cross-over trials) with anthocyanin-rich foods versus placebo or control intervention that assessment cardiometabolic factors. Results: We found 14 clinical trials that met the eligibility criteria, and we included 10 studies for the quantitative synthesis. For anthocyanin-rich foods versus control interventions, the mean difference (MD) for low-density lipoprotein (LDL) was − 7.98 mg/dL (CI = − 15.20 to − 0.77, GRADE: Very low). For homeostatic model assessment for insulin resistance (HOMA-IR), the MD was 0.04 (CI = 0.08 to 0.16, GRADE: Moderate). The MD for interleukin 6 was 0.00 pg/mL (CI = − 0.01 to 0.00, GRADE: Low). For tumor necrosis factor alpha (TNF-α), the standardized mean difference (SMD) was − 0.52 pg/mL (CI = 0.85 to 0.19 GRADE: Very low) when compared with the control interventions. The certainty of the evidence for the other outcomes it is very low. Conclusion: Our findings suggest that anthocyanin-rich foods could improve certain cardiometabolic markers (e.g., TC, TG, LDL, and TNF-α) among individuals with MetS (with very low quality evidence according to GRADE), compared with placebo or other control interventions. PROSPERO registration number: CRD42020187287.