Effects of Polyphenol-Rich Fruit Extracts on Diet-Induced Obesity in Rodents: Systematic Review and Meta-Analysis

Background: Obesity is a complex condition of high prevalence and cost to the public health system. Recent research has demonstrated the potential of natural products, such as polyphenol-rich fruit extracts, for use in the treatment of obesity. The goal of this systematic review and meta-analysis is to determine the metabolic effects of polyphenol-rich fruit extracts on diet-induced obesity (DIO) in rodents. Methods: We searched MEDLINE, EMBASE, and Web of Science databases to identify preclinical studies that assessed polyphenol-rich fruit extracts compared to placebo on DIO in rodents in December 2018. Two researchers selected the studies, extracted the data, and assessed the quality of studies. Meta-analyses of standardized mean difference (SMD) of outcomes were calculated in Stata 11, and causes of heterogeneity were assessed by meta-regression. Results: We included 14 studies in the systematic review and 13 studies with 21 matched groups in the metaanalysis. Polyphenol-rich fruit extracts reduced the total body weight gain (SMD = -1.48; confidence interval: - 1.95, -1.01), energy intake (SMD = -0.42; -0.67, -0.17), visceral adipose tissue (SMD = -0.96; -1.25, -0.66), triglycerides (SMD = -1.00; -1.39, -0.62), cholesterol (SMD = -1.18, -1.66, -0.69), LDL- c (SMD = -1.15; -1.65, - 0.65), fasting glucose (SMD = -1.05; -1.65, -0.46), and fasting insulin (SMD = -1.40; -1.80, -1.00) when compared to vehicle. Conclusion: Polyphenol-rich fruit extract had positive effects on weight gain, dyslipidaemia, insulin resistance at different doses, and fruit source in male mice.