The Combined Effects of Dietary Polyphenol and Exercise Intervention on Improving Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Context Both dietary polyphenols and exercise interventions independently improve cardiometabolic health. Combining both interventions are commonly used by trained athletes to improve performance, but there is a research gap regarding their effect on cardiometabolic health in an untrained population.

Objective The aim of this systematic review and meta-analysis was to investigate the combined effect of a dietary polyphenol and exercise (ExPo) intervention on cardiovascular and metabolic health, compared with Polyphenol Only control treatment or Exercise Only control treatment.

Data Sources A systematic search for relevant articles in the databases PubMed, Cochrane Library, and Scopus was carried out.

Data Extraction The mean difference (along with the standard deviation of this change) in outcomes from pre-intervention to post-intervention was extracted. The mean difference between the ExPo treatment and the Polyphenol Only control treatment (dietary polyphenol only intervention) or the Exercise Only control treatment (exercise only intervention) was compared to calculate the pooled effect size. The Cochrane Risk Of Bias tool for randomized controlled trials was employed for assessing the risk of bias.

Data Analysis Pooled effect size was computed as the weighted mean difference with a 95% CI, using a random-effect model, and presented as a forest plot. The between-study heterogeneity and between-subgroup heterogeneity was computed as I2. The robustness of the results was assessed by conducting sensitivity analyses, using the leave-one-out method and removing ambiguous data. Meta-analysis showed that the ExPo intervention significantly decreased triglycerides (−0.18, 95% CI [−0.37, 0.00] mmol/L) more than the Polyphenol Only control treatment. The ExPo intervention also significantly decreased glucose (−0.17, 95% CI [−0.32, −0.02]) and insulin (−14.43, 95% CI [−24.98, −3.87] pmol/L) more than the Exercise Only control treatment. No other beneficial effect from an ExPo intervention was found for blood pressure, anthropometry, body fat percentage, other lipid profile variables, or inflammatory marker variables.

Conclusion In conclusion, improvement in cardiometabolic health following an ExPo intervention compared with either of the control groups has been shown to be limited in an untrained population.

Systematic Review Registration PROSPERO registration No. CRD42024508608.