The effect of green leafy and cruciferous vegetable intake on the incidence of type 2 diabetes, cardiovascular disease and cancers: A meta-analysis.

摘要

Does the consumption of green leafy vegetables (GLV) including cruciferous vegetables (CV) significantly reduce the incidence of type 2 diabetes, cardiovascular disease (CVD), and different types of human cancers? These research questions were answered via employing the statistical methods of meta-analysis by synthesizing relevant worldwide studies that address the association between the consumption of GLV and risk of incidence of said diseases.;All meta-analysis calculations included determination of effect sizes of hazard ratio (HR), odds ratio (OR), relative risk (RR), and their respective 95% confidence intervals, heterogeneity of the studies, relative weights for each study, and significance (p) for each study. Five studies met the inclusion criteria that investigated the relationship between the incidences of type 2 diabetes with the intake of GLV. The overall effect size (random effect model) was: HR = 0.840 (95% CI 0.782 to 0.901), p<.001, which indicates a significant 16% reduced incidence of type 2 diabetes risk. Eight studies met the inclusion criteria that investigated the relationship between the incidences of total CVD with the intake of GLV. The overall effect size (random effect model) was: RR = 0.842 (95% CI 0.753 to 0.941), p=.002, which indicates a significant 15.8% reduced incidence of CVD. With just five and eight studies collected, these results cannot conservatively be generalized, and can only indicate "an observed trend" in regards to the reduction of type 2 diabetes and CVD.;Three Meta-Analyses examined the relationship between the incidences of Cancerous diseases with the intake of GLV: (a) Forty five studies using OR as the effect size were synthesized with an output of (random effect model) OR = 0.694 (95% CI 0.643 to 0.749), p<.001, indicating a significant 30.6% lower odds of incidence from 17 different cancers, (b) Nineteen studies using HR as the effect size were synthesized with an output of (random effect model) HR = 0.833 (95% CI 0.759 to 0.914), p<.001, indicating a significant 16.7% lower risk of incidence from 12 different cancers, and (c) Fifteen studies using RR as the effect size were synthesized with an output of (random effect model) RR = 0.911 (95% CI 0.857 to 0.969), p=.003, indicating a significant 8.9% lower risk of incidence from nine different cancers. All five meta-analyses results are consistent in demonstrating the efficacy of GLV intake in reducing the risk of incidence of Type 2 Diabetes, CVD, and certain Cancerous diseases.