Wang MX, et al. Lutein supplementation reduces plasma lipid peroxidation and C-reactive protein in healthy nonsmokers. Atherosclerosis. 2013;227:380-385.
In this randomized, double-blind, placebo-controlled trial, the effects of lutein supplementation on CVD biomarkers was evaluated in healthy nonsmokers. A total of 117 subjects were randomly assigned to receive either lutein 10 mg/d, lutein 20 mg/d, or placebo for 12 weeks. Plasma carotenoid concentrations, total antioxidant capacity (TAOC), lipoprotein profiles, and antioxidant enzyme levels were determined at baseline, as well as Weeks 6 and 12 after treatment initiation. Protein and lipid oxidative damage and C-reactive protein (CRP) concentrations were also measured at baseline and post-supplementation. During the 12-week treatment period, significant increases in plasma lutein and TAOC were observed for both treatment groups. In addition, malondialdehyde levels were significantly reduced in the 20-mg lutein group, indicating a decrease in lipid peroxidation. Decreases in CRP concentration were dose-dependent with lutein, with significant between-group differences for lutein 20 mg/d versus placebo. For both active treatment groups, serum CRP was directly related to changes in plasma lutein and TAOC. Investigators concluded these findings preliminarily support a reduction in CVD biomarkers with lutein supplementation.
Ros MM, et al. Plasma carotenoids and vitamin C concentrations and risk of urothelial cell carcinoma in the European Prospective Investigation into Cancer and Nutrition. Am J Clin Nutr. 2012 Oct;96(4):902-10.
This study involved 856 patients with newly diagnosed urothelial cell carcinoma (UCC) who were matched with 856 cohort members by sex, age at baseline, study center, date and time of blood collection, and fasting status. Plasma carotenoids including alpha- and beta-carotenes, beta-cryptoxanthin, lycopene, lutein, and zeaxanthin were measured by using reverse-phase HPLC. Plasma vitamin C was measured by a colorimetric assay. Incidence rate ratios (IRRs) were estimated using conditional logistic regression with adjustment for smoking status, duration, and intensity. Researchers reported that risk of UCC decreased with greater concentrations of plasma carotenoids (IRR for highest quartile compared with the lowest: 0.64; 95% CI: 0.44, 0.93; P-trend = 0.04). Plasma lutein was inversely associated with risk of nonaggressive UCC (IRR: 0.56; 95% CI: 0.32, 0.98; P-trend = 0.05). Plasma beta-carotene was also inversely associated with aggressive UCC (IRR: 0.51; 95% CI: 0.30, 0.88; P-trend = 0.02), but no association was observed between plasma vitamin C and risk of UCC. Investigators concluded there is some evidence of a protective role with greater concentrations of plasma lutein and beta-carotene to reduce the risk of UCC, but that residual confounding by smoking and other factors could not be excluded.
Christen WG, et al. Dietary carotenoids, vitamins C and E, and risk of cataract in women: a prospective study. Arch Ophthalmol . Jan 2008;126(1):102-109.
To determine the effects of dietary carotenoids on cataract formation in women, this prospective observational study was undertaken with 35,551 female participants for 10 years. Cataract formation and visual acuity were the primary outcome measures. Increased dietary lutein/zeaxanthin was associated with an 18% reduced risk of cataract formation. Randomized clinical trials of lutein/zeaxanthin in both men and women are necessary to determine if lutein supplementation may also reduce cataract risk.