Effect of lycopene supplementation on oxidative stress: an exploratory systematic review and meta-analysis of randomized controlled trials.

Journal of medicinal food
Q3
May 2013
Citations:69
Influential Citations:2
Systematic Reviews / Meta-Analyses
81
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Methods
Thirteen randomized controlled trials across the United States, Canada, Ireland, Spain, Germany, Italy, Iran, France, and Korea, including 844 participants. Populations included healthy adults and patients such as men with newly diagnosed prostate cancer, individuals with type 2 diabetes mellitus, and those with mildly elevated cholesterol. Trial sizes ranged from 26 to 175 participants; mean age 25.9–70 years; mean BMI 21.0–28.5 kg/m2 (across 10 trials). Study designs included 1 crossover trial and 12 parallel trials; eight trials were double-blind, two were single-blind, and three reported no blinding information.
Intervention
Oral lycopene supplementation; formulations varied: purified lycopene; lycopene with small amounts of tocopherol; lycopene capsules containing 10% beta-carotene; and lycopene with metabolites (phytoene and phytofluene) plus tocopherol and beta-carotene. Doses included 15 mg/day and 30 mg/day; duration at least 7 days; taken orally.
Results
Lycopene supplementation significantly reduced DNA tail length in lymphocytes measured by comet assay (mean difference -6.27; 95% CI -10.74 to -1.90; P = 0.006) across 3 trials (n=115). LDL lag time did not show a significant prolongation (MD 3.76; 95% CI -2.48 to 10.01; P = 0.24). Overall, lycopene may alleviate oxidative stress, but biomarker results are inconsistent and heterogeneous, limiting firm conclusions about health benefits. Some clinical signals (e.g., lower PSA and less advanced tumor pathology in prostate cancer in one trial; improvements in certain endothelial and inflammatory markers in subgroups) were observed but were not consistently replicated. Given the heterogeneity and limited evidence, authors conclude that consuming natural carotenoid-rich fruits and vegetables is preferable to purified lycopene supplementation until stronger evidence emerges.
Limitations
Small and heterogeneous set of trials; substantial variability in formulations, doses, populations, and outcome measures; potential biases due to incomplete blinding and allocation concealment reporting; some trials included co-supplements; one crossover design with potential carryover effects; limited number of studies contributing to meta-analyses and inconsistent biomarker assays limit generalizability.

Abstract

Lycopene is a potentially useful compound for preventing and treating cardiovascular diseases and cancers. Studies on the effects of lycopene on oxidative stress offer insights into its mechanism of action and provide evidence-based rationale for its...