Tomato and lycopene supplementation and cardiovascular risk factors: a systematic review and meta-analysis

Background and aims Epidemiological evidence suggests an association between consumption of tomato products or lycopene and lower risk for cardiovascular diseases (CVD). Our aim was to evaluate the state of the evidence from intervention trials on the effect of consuming tomato products and lycopene on markers of cardiovascular (CV) function. We undertook a systematic review and meta-analysis on the effect of supplementing tomato and lycopene on CV risk factors. Methods Three databases including Medline, Web of science, and Scopus were searched from inception to August 2016. Inclusion criteria were: intervention randomised controlled trials reporting effects of tomato products and lycopene supplementation on CV risk factors among adult subjects >18 years of age. The outcomes of interest included blood lipids (total-, HDL-, LDL-cholesterol, triglycerides, oxidised-LDL), endothelial function (flow-mediated dilation (FMD), pulse wave velocity (PWV)) and blood pressure (BP) inflammatory factors (CRP, IL-6) and adhesion molecules (ICAM-1). Random-effects models were used to determine the pooled effect sizes. Results Out of 1189 publications identified, 21 fulfilled inclusion criteria and were meta-analysed. Overall, interventions supplementing tomato were associated with significant reductions in LDL-cholesterol (−0.22 mmol/L; p = 0.006), IL-6 (standardised mean difference −0.25; p = 0.03), and improvements in FMD (2.53%; p = 0.01); while lycopene supplementation reduced Systolic-BP (−5.66 mmHg; p = 0.002). No other outcome was significantly affected by these interventions. Conclusions The available evidence on the effects of tomato products and lycopene supplementation on CV risk factors supports the view that increasing the intake of these has positive effects on blood lipids, blood pressure and endothelial function. These results support the development of promising individualised nutritional strategies involving tomatoes to tackle CVD.