Table 1.
PICOS (population, intervention, comparison, outcome, and study design) criteria for inclusion of studies.
Fig 1.
Flow chart of the studies selection process.
Table 2.
General characteristics of the included studies.
Table 3.
Quality assessment of studies using Jadad scale.
Fig 2.
Forest plot of studies investigating the effect of polyphenol supplementation on executive functions for all the primary studies.
Fig 3.
Funnel plot of standard errors by hedges g showing both observed and adjusted effect summary for all the primary studies.
Fig 4.
Forest plot of the subgroup meta-analysis for the between participants RCTs (BTW-P RCT) and crossover studies (CO) using random effect model.
Fig 5.
Sub-group meta-analysis for the between participants RCTs (BTW-P RCT) and crossover studies administering flavonoids.
Fig 6.
Sub-group meta-analysis for the studies which administered isoflavone.
Fig 7.
Sub-group meta-analysis for the between participants RCTs studies which administered resveratrol using fixed effect model.
Fig 8.
Sub-group meta-analysis for the between participants RCTs studies which administered resveratrol using random effect model.