Dietary Intakes of Green Leafy Vegetables and Incidence of Cardiovascular Diseases

Aim: Low- and middle-income countries (LMICs) are currently experiencing increasing cardiovascular disease (CVD) rates. Green leafy vegetables (GLV), which are abundant in these countries, are known to be particularly rich in cardioprotective nutrients. This study sought to determine the specific effect of GLV intake on the incidence of CVD.

Methods: Previously published cohort studies on GLV intake and incidence of CVD were retrieved through a systematic search of Google Scholar, EMBASE, MEDLINE, HINARI and Cochrane Library. A methodological evaluation of studies was carried out using the network of Ottawa scale, and a fixed-effect meta-analysis was applied to estimate pooled relative risk (RR) and 95% confidence interval (CI). Heterogeneity was determined using the I statistic. Sensitivity analysis was done using the leave-one-study-out technique. All statistical analysis was carried out at < 0.05 using RevMan 5.4.

Results: The pooled RR (95% CI) of incident CVD events from 17 studies was 0.93 (0.92-0.95). Specifically, GLV intake was inversely related with incident cerebral infarction (RR: 0.92; 95% CI: 0.88-0.96), heart disease (RR: 0.93; 95% CI: 0.87-0.99) and other CVD events (RR: 0.95; 95% CI: 0.93-0.98).

Conclusions: GLV intake was associated with a lower incidence of CVD, and may be a promising primary-prevention strategy against CVD events. The findings are especially important in LMICs where the burden of CVD remains high.