The effects of lutein on respiratory health across the life course: A systematic review

Background: Lutein, a fat-soluble carotenoid present in green leafy vegetables and eggs, has strong antioxidant properties and could therefore be important for respiratory health. Design: We systematically reviewed the literature for articles that evaluated associations of lutein (intake, supplements or blood levels) with respiratory outcomes, published in Medline, Embase, Cochrane Central, PubMed, Web of Science and Google Scholar, up to August 2014. Results: We identified one Randomized Control Trial (RCT), two longitudinal, four prospective and six cross-sectional studies. The individual studies obtained a Quality Score ranging between 3 and 9. Six studies were performed in children, which examined bronchopulmonary dysplasia (BPD), asthma and wheezing. In adults, 7 studies investigated asthma, respiratory function and respiratory mortality. The RCT found a borderline significant effect of lutein/zeaxanthin supplementation in neonates on the risk of BPD (OR 0.43 (95% CI 0.15; 1.17). No association was found between lutein intake or levels and respiratory outcomes in children. A case–control study in adults showed lower lutein levels in asthma cases. Three studies, with a prospective or longitudinal study design, in adults found a small but a significant positive association between lutein intake or levels and respiratory function. No association was found in the other two studies. In relation to respiratory mortality, one longitudinal study showed that higher lutein blood levels were associated with a decreased mortality (HR 0.77 (95% CI 0.60; 0.99), per SD increase in lutein). Conclusion: The published literature suggests a possible positive association between lutein and respiratory health. However, the literature is scarce and most studies are of observational nature.