The effect of apple cider vinegar on lipid profiles and glycemic parameters: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND: Elevated lipid profiles and impaired glucose homeostasis are risk factors for several cardiovascular diseases (CVDs), which, subsequently, represent a leading cause of early mortality, worldwide. The aim of the current study was to conduct a systematic review and meta-analysis of the effect of apple cider vinegar (ACV) on lipid profiles and glycemic parameters in adults. METHODS: A systematic search was conducted in electronic databases, including Medline, Scopus, Cochrane Library, and Web of Knowledge, from database inception to January 2020. All clinical trials which investigated the effect of ACV on lipid profiles and glycemic indicators were included. Studies were excluded if ACV was used in combination with other interventions or when the duration of intervention was < 2 weeks. To account for between-study heterogeneity, we performed meta-analysis using a random-effects model. RESULTS: Overall, nine studies, including 10 study arms, were included in this meta-analysis. We found that ACV consumption significantly decreased serum total cholesterol (− 6.06 mg/dL; 95% CI: − 10.95, − 1.17; I(2): 39%), fasting plasma glucose (− 7.97 mg/dL; 95% CI: − 13.74, − 2.21; I(2): 75%), and HbA1C concentrations (− 0.50; 95% CI: − 0.90, − 0.09; I(2): 91%). No significant effect of ACV consumption was found on serum LDL-C, HDL-C, fasting insulin concentrations, or HOMA-IR. The stratified analysis revealed a significant reduction of serum TC and TG in a subgroup of patients with type 2 diabetes, those who took ≤15 mL/day of ACV, and those who consumed ACV for > 8-weeks, respectively. Furthermore, ACV consumption significantly decreased FPG levels in a subgroup of studies that administered ACV for > 8-weeks. Further, ACV intake appeared to elicit an increase in FPG and HDL-C concentrations in apparently healthy participants. CONCLUSION: We found a significant favorable effect of ACV consumption on FPG and blood lipid levels. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12906-021-03351-w.