The level and efficacy of lutein in patients with age-related macular degeneration: a comprehensive systematic review and meta-analysis.

Background: Lutein has been linked with various visual performance disorders, including age-related macular degeneration (AMD). However, previous studies evaluating the association between serum lutein and the risk of AMD showed results, and the efficacy of lutein intake in AMD patients remains unclear. Methods: To comprehensively estimate the relationship between lutein and AMD, a systematic review and meta-analysis was conducted by searching eligible randomized clinical trials (RCT) and case-control studies to study the association between lutein and AMD on the Cochrane Library, MEDLINE, Elsevier, PubMed, Web of Knowledge, Chinese National Knowledge Infrastructure (CNKI), and Chinese Biomedical Database (CBM) databases until April 2020. The weighted mean difference (WMD) with 95% confidence interval (95% CI) was adopted as the primary effect estimate. Meta-analysis was conducted using STATA 12.0. Results: Nine studies with 855 participants were included in this meta-analysis. The NOS scoring of five case-control studies ranged 5-9. For RCTs, two studies were rated with a low risk of bias, one study with a moderate risk of bias and one with a high risk of bias. The results increased significantly in macular pigment optical density (MPOD) (WMD =0.069; 95% CI: 0.040-0.098, P=0.000) among AMD patients taking lutein supplementation, while there was no difference in circulating lutein levels between AMD patients and controls (WMD =0.00; 95% CI: -0.01 to 0.00, P=0.310). Subgroup analysis suggested that the dose and duration of supplementation could significantly influence the MPOD level in AMD patients. In particular, we observed a larger increase in MPOD of AMD patients using a higher dose (20 mg/d) and longer treatment (>6 months). Conclusions: Although current evidence does not support circulating lutein as a biomarker for early screening of the high-risk AMD population, this study is the first meta-analysis to explore the relationship between lutein in blood and AMD patients. Given that lutein has a high safety profile as indicated by many studies, it is reasonable to give the current analysis result that high dose (20 mg/d) and long duration (>6 months) of lutein intake could be beneficial to AMD patients.