Abstract
Objectives
This review has an objective to determine the effectiveness of polyphenol intervention for the primary prevention of cardiovascular disease events and others surrogate endpoint which may correlate with cardiovascular disease events
Data Sources
These electronic databases were used to search the appropriate trials: MEDLINE (OvidSP, 1946 to March week 2 2020); The Cochrane Central Register of Controlled Trials (CENTRAL,week 2 March 2020). We only used English language trials that were available on these two databases.
Review Methods
We chose randomized controlled trials both in healthy or having high risk of cardiovascular diseases. Polyphenol as intervention was described as any food or drink that has polyphenol or its derived substance as main content. Placebo or no intervention is the comparison group. Cardiovascular clinical events and surrogate endpoints or cardiovascular disease risk factors are included in the outcome. Revman 5.5 software was used to analyze all the trials and to assess the risk of bias each trial. We selected random or fixed effects depend on the heterogeneity between trials in the meta analysis.
Results
Seven trials were included with 49200 participants randomized. Heterogeneity was shown between trials regarding the characteristic of participants, types of polyphenol intervention, and follow up periods. Cardiovascular event outcomes are only available in one trial (Howard et al 2006), with the intervention not clearly defined as polyphenol but increasing fruit and grain consumption. This trial shows no evidence was shown on fatal and non-fatal cardiovascular outcome by consuming more fruit and grain with 8 years mean of follow up. By analyzing remaining trials, which provide surrogate endpoints or cardiovascular risk factors, there is no evidence that polyphenol intervention reduce systolic and diastolic blood pressure, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol level, and triglyceride level. However, reduction total cholesterol level was shown from the baseline (MD -5.41 mg/dl, 95% CI -8.21 to -2.62, P=0.0001). Subgroup analyses were done with dividing the trials that involve women only and both men and women. This analysis shows the reduction of both systolic (MD -2.78 mmHg, 95% CI -5.47 to -0.08, P=0.04) and diastolic blood pressure (MD -2.59 mmHg, 95% CI -4.84 to -0.34, P=0.02) in trials involving both men and women. A sensitivity analysis was done by excluding the trials with risk of bias with no different results effect. Moreover, not any trials reported adverse events of polyphenol.
Author’s Conclusion
Due to the limitation evidence or trial available, we could not obtain meta analysis on the primary outcome. Nevertheless, this review suggests that polyphenol intervention does show favorable effect on surrogate endpoints which was total cholesterol levels. Besides, systolic blood pressure and diastolic blood pressure in trials which involves both men and women also shown an improvement. The high heterogeneity in this review also suggests that more evidence are needed to assess the effectiveness of polyphenol intervention in reducing cardiovascular event outcomes and risk factors in the future.
Genome-wide pleiotropy analysis identifies novel blood pressure variants and improves its polygenic risk scores
