Effect of Intake of Lycopene-Containing Products on Vascular Endothelial Function in Healthy Adults: A Systematic...

Background/Objectives: Vascular endothelial dysfunction is an early marker of cardiovascular disease. Lycopene, a naturally red carotenoid with strong antioxidant activity, may improve vascular endothelial function. This systematic review and meta-analysis examined lycopene's effects on vascular endothelial function in healthy adults in the context of cardiovascular risk assessment. Methods: In June 2026, we searched four literature databases (Ichushi-Web, PubMed, Cochrane Central Register of Controlled Trials, and Global Index Medicus), three clinical trial registries (International Clinical Trial Registry Platform, ClinicalTrials.gov, and University Hospital Medical Information Network Clinical Trials Registry), and notification information for Foods with Function Claims, using peer-reviewed search strategies. We extracted human intervention studies assessing oral lycopene intake and vascular endothelial function. Two authors independently selected eligible studies and assessed the risk of bias. Data were pooled as mean differences (MDs) and analyzed using a random-effects model. The protocol was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN000058348). Results: Six studies were included in this systematic review. A meta-analysis of four continuous (≥7 days) lycopene-containing product intake studies measuring flow-mediated dilation (FMD) (n = 182) revealed a significant increase in FMD (MD = 1.36, 95% confidence interval: 0.20, 2.51, p = 0.02). The certainty of the evidence across the four studies was limited and moderate. One study not included in the meta-analysis showed that 15 mg of lycopene intake for 8 weeks significantly increased the reactive hyperemia peripheral arterial tonometry index. Conclusions: This systematic review/meta-analysis with limited and moderate certainty evidence suggests that the continuous intake of lycopene-containing products may have beneficial effects on vascular endothelial function in healthy adults. However, the findings were derived from a small-scale meta-analysis in which the result was no longer statistically significant after the exclusion of one study.