Protective effect of lycopene on serum cholesterol and blood pressure: Meta-analyses of intervention trials

Background: Cardiovascular disease is associated with oxidative stress, inflammatory processes, and vascular dysfunction. Lycopene, a carotenoid found in tomatoes, is an antioxidant with a protective effect on lipid peroxidation and anti-atherosclerotic capacity. This review summarises current evidence on the effect of lycopene on serum lipid concentrations and blood pressure. Methods: We searched the PubMed and Cochrane databases for intervention studies between 1955 and September 2010 investigating the effect of lycopene on blood lipids or blood pressure for a minimum duration of 2 weeks. We conducted meta-analyses using a random effect model of all studies fitting the inclusion criteria. Additionally, we conducted subgroup meta-analysis of serum lipid concentrations by lycopene dosage and subgroup meta-analysis by baseline blood pressure. Results: Twelve studies (13 trial arms) meeting the inclusion criteria investigated the effect of lycopene on serum lipids, and four studies examined its effect on blood pressure. Meta-analysis on serum lipids revealed a significant cholesterol-lowering effect of lycopene for total serum cholesterol (mean change +/- SE: -7.55 +/- 6.15 mg/dl: p = 0.02) and low-density-lipoprotein (LDL) cholesterol (mean change +/- SE: -10.35 +/- 5.64 mg/dl, p = 0.0003) in the subgroup of trials using lycopene dosages of >= 25 mg daily, whereas subgroup meta-analysis of trials using lower lycopene dosages was not significant. Meta-analysis of the effect of lycopene on systolic blood pressure of all trials suggested a significant blood pressure reducing effect (mean systolic blood pressure change +/- SE: -5.60 +/- 5.26 mm Hg, p = 0.04). Conclusions: Our meta-analysis suggests that lycopene taken in doses >= 25 mg daily is effective in reducing LDL cholesterol by about 10% which is comparable to the effect of low doses of statins in patient with slightly elevated cholesterol levels. More research is needed to confirm suggested beneficial effects on total serum cholesterol and systolic blood pressure. (C) 2010 Elsevier Ireland Ltd. All rights reserved.