Dietary and circulating lycopene and stroke risk: a meta-analysis of prospective studies

Epidemiological studies support a protective role of lycopene against stroke occurrence or mortality, but the results have been conflicting. We conducted a meta-analysis to assess the relationship between dietary or circulating lycopene and stroke risk (including stroke occurrence or mortality). Relevant papers were collected by screening the PubMed database through October 2013. Only prospective studies providing relative risk estimates with 95% confidence intervals for the association between lycopene and stroke were included. A random-effects model was used to calculate the pooled estimate. Subgroup analysis was conducted to investigate the effects of various factors on the final results. The pooled analysis of seven prospective studies, with 116,127 participants and 1,989 cases, demonstrated that lycopene decreased stroke risk by 19.3% (RR=0.807, 95% CI=0.680-0.957) after adjusting for confounding factors. No heterogeneity was observed (p=0.234, I2=25.5%). Circulating lycopene, not dietary lycopene, was associated with a statistically significant decrease in stroke risk (RR=0.693, 95% CI=0.503-0.954). Lycopene could protect European, or males against stroke risk. Duration of follow-up had no effect on the final results. There was no evidence of publication bias. Lycopene, especially circulating lycopene, is negatively associated with stroke risk.