Abstract
BackgroundThe acute effects of grape polyphenols on endothelial function in adults are inconsistent. Here, we performed meta-analyses to determine these acute effects as measured by flow-mediated dilation (FMD).MethodsTrials were searched in PubMed, Embase and the Cochrane Library database. Summary estimates of weighted mean differences (WMDs) and 95% CIs were obtained by using random-effects models. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity. The protocol details of our meta-analysis have been submitted to the PROSPERO register and our registration number is CRD42013004157.ResultsNine studies were included in the present meta-analyses. The results showed that the FMD level was significantly increased in the initial 120 min after intake of grape polyphenols as compared with controls. Meta-regression and subgroup analyses were performed and showed that a health status was the main effect modifier of the significant heterogeneity. Subgroups indicated that intake of grape polyphenols could significantly increase FMD in healthy subjects, and the increased FMD appeared to be more obviously in subjects with high cardiovascular risk factors. Moreover, the peak effect of grape polyphenols on FMD in healthy subjects was found 30 min after ingestion, which was different from the effect in subjects with high cardiovascular risk factors, in whom the peak effect was found 60 min after ingestion.ConclusionsEndothelial function can be significantly improved in healthy adults in the initial 2 h after intake of grape polyphenols. The acute effect of grape polyphenols on endothelial function may be more significant but the peak effect is delayed in subjects with a smoking history or coronary heart disease as compared with the healthy subjects.
Highlights
Atherosclerosis is the primary pathophysiological basis for most cardiovascular diseases [1], and endothelial dysfunction has been considered an early feature in the progression of atherosclerosis and an independent predictor of poor prognosis in many cardiovascular diseases [2,3]
The remaining 18 articles were excluded for the following reasons: the enrolled subjects were adolescents but not adults [21,22]; there were no control groups in the studies [23,24], or all the groups designed in the studies used grape polyphenols and no blank control groups were included [25,26]; the baseline flow-mediated dilation (FMD) was not measured in one trial [27]; the exact values of FMD were not reported in three trials [28,29,30]; the measurements of FMD were based on the peak blood alcohol concentration, but not at fixed times in one study [31]; there were 7 trials investigating the chronic but not acute effects of grape polyphenols on the endothelial function [32,33,34,35,36,37,38]
Subgroup analysis based on the health status of enrolled subjects was performed and the results showed that the grape polyphenols could significantly increase FMD level 30 min after the intervention in the healthy subgroup (6 comparisons; weighted mean differences (WMDs):2.55%; 95% CI: 1.28, 3.82; P,0.0001)
Summary
Atherosclerosis is the primary pathophysiological basis for most cardiovascular diseases [1], and endothelial dysfunction has been considered an early feature in the progression of atherosclerosis and an independent predictor of poor prognosis in many cardiovascular diseases [2,3]. The intriguing results in vitro and animal studies encouraged people to investigate the effects of grape polyphenols on endothelial function in adults. Due to the rapidly metabolized feature of polyphenols [11], most clinical trials in adults have focused on the acute effects of grape polyphenols on endothelial function [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38]. The acute effects of grape polyphenols on endothelial function in adults are inconsistent. We performed meta-analyses to determine these acute effects as measured by flow-mediated dilation (FMD)
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