Dietary Green Leafy Vegetables and Cardiovascular Disease Risk: A Systematic Review and Meta-Analysis

Area of Science:

• Nutrition Science
• Cardiovascular Health
• Epidemiology

Background:

• Observational studies suggest green leafy vegetables (GLV) intake may reduce cardiovascular disease (CVD) risk.
• Inconsistencies exist between observational findings and randomized controlled trials (RCTs) regarding GLV and CVD.
• A comprehensive synthesis of evidence from diverse study designs is crucial.

Purpose of the Study:

• To evaluate the association between GLV consumption and CVD risk.
• To assess the impact of GLV on cardiovascular risk factors like blood pressure (BP) and endothelial function.
• To synthesize evidence from both observational studies and RCTs.

Main Methods:

• Systematic literature searches conducted across major databases (PubMed, EMBASE, APA PsycInfo, Ovid).
• Risk of bias assessed using ROBINS-E for observational studies and RoB 2 for RCTs.
• Random-effects meta-analyses performed for pooled relative risks (observational) and mean differences (RCTs).

Main Results:

• Higher GLV consumption associated with reduced CVD risk (RR: 0.89) and mortality (RR: 0.79) in observational studies.
• RCTs (n=7) showed no significant improvement in vascular function (MD: -0.37).
• No significant associations found between GLV intake and hypertension risk or blood pressure changes in RCTs.

Conclusions:

• Observational data suggest a potential cardioprotective role for higher GLV consumption.
• Evidence from RCTs is currently limited and inconclusive regarding GLV's direct impact on vascular function.
• Further well-designed clinical trials are necessary to confirm associations and elucidate mechanisms.