Dietary vitamin and carotenoid intake and risk of age-related cataract.

Background: Existing studies suggest that dietary vitamins and carotenoids might be associated with a reduced risk of age-related cataract (ARC), although a quantitative summary of these associations is lacking. Objectives: The aim of this study was to conduct a meta-analysis of randomized controlled trials (RCTs) and cohort studies of dietary vitamin and carotenoid intake and ARC risk. Methods: The MEDLINE, EMBASE, ISI Web of Science, and Cochrane Library databases were searched from inception to June 2018. The adjusted RRs and corresponding 95% CIs for the associations of interest in each study were extracted to calculate pooled estimates. Dose-response relations were assessed with the use of generalized least-squares trend estimation. Results: We included 8 RCTs and 12 cohort studies in the meta-analysis. Most vitamins and carotenoids were significantly associated with reduced risk of ARC in the cohort studies, including vitamin A (RR: 0.81; 95% CI: 0.71, 0.92; P = 0.001), vitamin C (RR: 0.80; 95% CI: 0.72, 0.88; P < 0.001), vitamin E (RR: 0.90; 95% CI: 0.80, 1.00; P = 0.049), ß-carotene (RR: 0.90; 95% CI: 0.83, 0.99; P = 0.023), and lutein or zeaxanthin (RR: 0.81; 95% CI: 0.75, 0.89; P < 0.001). In RCTs, vitamin E (RR: 0.97; 95% CI: 0.91, 1.03; P = 0.262) or ß-carotene (RR: 0.99; 95% CI: 0.92, 1.07; P = 0.820) intervention did not reduce the risk of ARC significantly compared with the placebo group. Further dose-response analysis indicated that in cohort studies the risk of ARC significantly decreased by 26% for every 10-mg/d increase in lutein or zeaxanthin intake (RR: 0.74; 95% CI: 0.67, 0.80; P < 0.001), by 18% for each 500-mg/d increase in vitamin C intake (RR: 0.82; 95% CI: 0.74, 0.91; P < 0.001), by 8% for each 5-mg/d increase in ß-carotene intake (RR: 0.92; 95% CI: 0.88, 0.96; P < 0.001), and by 6% for every 5 mg/d increase in vitamin A intake (RR: 0.94; 95% CI: 0.90, 0.98; P < 0.001). Conclusions: Higher consumption of certain vitamins and carotenoids was associated with a significant decreased risk of ARC in cohort studies, but evidence from RCTs is less clear.

Effect of lutein supplementation on visual function in nonproliferative diabetic retinopathy.

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine whether supplementation with lutein improved visual function in patients with nonproliferative diabetic retinopathy (NPDR). METHODS AND STUDY DESIGN: In this randomized, double-blind, placebo-controlled trial, 31 patients with NPDR were assigned randomly to 10 mg/d of lutein or identical placebo for 36 weeks. Visual performance indices, including visual acuity (VA), contrast sensitivity (CS) and glare sensitivity (GS) at four different spatial frequencies, were measured at baseline, week 18 and 36. RESULTS: At 36 weeks, a slight improvement in VA was found in the lutein group. A significant association was observed between the changes in VA and the corresponding baseline values in treatment group (r=-0.53; p=0.04). At 36 weeks, the lutein treatment group increased CS at four spatial frequencies, and the improvement achieved statistical significance at 3 cycles/degree (p=0.02). The changes in CS at 3 cycles/degree for the lutein group was marginally significantly greater than those for the placebo group (p=0.09). There was also a slight increase in GS in the lutein group up to week 36, however, no significant changes were found over time in any cycles/degree. CONCLUSIONS: In patients with NPDR, supplementation with lutein resulted in potential improvements in CS at low spatial frequency. Further studies are required to determine the possibility that such intervention could be used as an adjunct therapy to prevent vision loss in diabetic patients.