Effects of lycopene intake on HDL-cholesterol and triglyceride levels: A systematic review with meta-analysis

Lycopene is a lipophilic unsaturated carotenoid and has a very strong singlet oxygen-quenching ability. Increased serum or plasma lycopene levels have been reported to be associated with a lower risk of metabolic syndrome. We aimed to investigate the effects of lycopene intake on blood HDL-cholesterol (HCL-c) and triglyceride (TG) levels, which are metabolic syndrome biomarkers, by systematic review and meta-analyses of human interventional trials. We searched 15 databases and included studies that assessed the effects of oral lycopene intake on blood HDL-c and TG levels of participants ≥18 years of age. Three reviewers independently selected applicable studies, then assessed study qualities. Data were pooled as standardized mean difference (SMD) and analyzed by random-effects model. Heterogeneity was assessed by I² statistics. Meta-analysis including 12 trial arms (n = 781) revealed a significantly increased HDL-c level in the lycopene group compared with that in the control group (SMD = 0.33 [95% CI: 0.12, 0.54], p = 0.002) and moderate heterogeneity (I²  = 45%). Most subgroup meta-analyses (restricted to study design, test food type, intake period, and participants' characteristics) showed similar results for HDL-c level. On the other hand, meta-analysis including 11 studies (n = 854) revealed no significant difference in TG level between the lycopene and control groups. Most studies which met eligibility criteria had moderate risk of bias. Funnel plots for HDL-c and TG suggested an absence of publication bias. In conclusion, this systematic review and meta-analyses suggested that lycopene intake significantly improved blood HDL-c levels but not TG levels.