Blueberry improves components of metabolic syndrome in animal studies: a systematic review and meta-analysis

Abstract

Metabolic syndrome (MetS) is the co-occurrence of several interconnected metabolic disorders and its prevalence is rising in the world. We hypothesized that blueberry (BB) feeding will have positive effects on components of MetS according to studies which used animal subjects. A systematic search for the studies in Science Direct, Embase, Cochrane and PubMed databases was done. The Studies which investigated effects of BB on components of MetS in animal models were included. Of 1030 potentially relevant studies, after investigation, 28 animal studies remained for further investigation. Of these, 1 study was conducted using pigs, one study using hamsters, 15 studies using mice and 11 studies using rats. 18 studies were eligible for the meta-analysis, and others were included in systematic review. The meta-analysis was done by Comprehensive Meta-analysis Software.The results of the meta-analysis demonstrated no significant effect of blueberry feeding on body weight [p = 0.65 CI95%: (-3.029, 1.892)]. However, a statistically significant improvement of systolic blood pressure [p < 0.001, CI95%: (-0.916, -0.283)], diastolic blood pressure[p = 0.01, CI95%: (-1.10, -0.13)], triglycerides[p = 0.01, CI95%: (-1.018, -0.109], total cholesterol [p < 0.001 CI95%: (-1.693, -0.782)], low density lipoprotein(LDL) [p = 0.008, CI95%: (-2.182, -0.334)], high density lipoprotein(HDL) [p = 0.02, CI95%: (0.077, 1.057)], blood glucose [p < 0.001, CI95%:( -1.638, -0.623)] and insulin level [p < 0.001, CI95%: (-1.711, -0.688)] was reported. Conclusion: this study showed that blueberry can be effective in ameliorating some components of metabolic syndrome in animal models. There is a need to conduct more studies on this subject in humans.