The Effect of Anthocyanin-Rich Foods or Extracts on Vascular Function in Adults: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Abstract

Anthocyanins are of interest due to their anti-oxidative and vasodilatory properties. Earlier reviews have shown that berries and other anthocyanin rich foods or extracts can improve vascular health, however the effect of anthocyanins on vascular function has not yet been reviewed. To address this gap in the literature, we conducted a systematic review and meta-analysis of randomised-controlled trials examining anthocyanin-rich foods or extracts on measures of vascular reactivity and/or stiffness in adults. Data from 24 studies were pooled as standardized mean difference (SMD) with 95% confidence intervals (CI). Anthocyanin consumption significantly improved flow-mediated dilation (FMD) following acute (SMD: 3.92%, 95% CI: 1.47, 6.38, p = 0.002; I² = 91.8%) and chronic supplementation (SMD: 0.84%, 95% CI: 0.55, 1.12, p = 0.000; I² = 62.5%). Pulse wave velocity was improved following acute supplementation only (SMD: -1.27 m/s, 95% CI: -1.96, -0.58, p = 0.000; I² = 17.8%). These results support the findings of previous reviews that anthocyanin rich foods or extracts may indeed improve vascular health, particularly with respect to vascular reactivity measured by FMD. More research is required to determine the optimal dosage, and the long-term effects of consumption.

Keywords: anthocyanins; berries; cardiovascular; flow-mediated dilation; vascular function; vascular reactivity; vascular stiffness.

Figure 1

Flow diagram of publication selection.

Figure 2

Jadad quality assessment of eligible studies; Abbreviations: A, Acute study; A1, Acute study 1; A2, Acute study 2; C, Chronic study.

Figure 3

Acute effects of anthocyanins relative to control for vascular reactivity (assessed via FMD and RHI). The forest plot has one line representing each study in the meta-analysis, plotted according to the mean difference (indicated by the black diamond in each line). The horizontal line joins the lower and upper limits of the 95% CI of these effects. The black diamond at the bottom of each graph represents the average effect size for FMD and RHI studies. The red diamond represents the average effect size for all studies assessing vascular reactivity.

Figure 4

Acute effects of anthocyanins relative to control for vascular stiffness (assessed via PWV and AI). The forest plot has one line representing each study in the meta-analysis, plotted according to the mean difference (indicated by the black diamond in each line). The horizontal line joins the lower and upper limits of the 95% CI of these effects. The black diamond at the bottom of each graph represents the average effect size for PWV and AI studies. The red diamond represents the average effect size for all studies assessing vascular reactivity.

Figure 5

Chronic effects of anthocyanins relative to control for vascular reactivity (assessed via FMD and RHI). The forest plot has one line representing each study in the meta-analysis, plotted according to the mean difference (indicated by the black diamond in each line). The horizontal line joins the lower and upper limits of the 95% CI of these effects. The black diamond at the bottom of each graph represents the average effect size for FMD and RHI studies. The red diamond represents the average effect size for all studies assessing vascular reactivity.

Figure 6

Chronic effects of anthocyanins relative to control for vascular stiffness (assessed via PWV and AI). The forest plot has one line representing each study in the meta-analysis, plotted according to the mean difference (indicated by the black diamond in each line). The horizontal line joins the lower and upper limits of the 95% CI of these effects. The black diamond at the bottom of each graph represents the average effect size for PWV and AI studies. The red diamond represents the average effect size for all studies assessing vascular reactivity.