Review The effects of lutein on respiratory health across the life course: A systematic review Debora Melo van Lent a , Elisabeth T.M. Leermakers a , Sirwan K.L. Darweesh a , Eduardo M. Moreira a , Myrte J. Tielemans a , Taulant Muka a , Anna Vitezova a , Rajiv Chowdhury b , Wichor M. Bramer c , Guy G. Brusselle a, d, e , Janine F. Felix a , Jessica C. Kiefte-de Jong a, f, *, 1 , Oscar H. Franco a, 1 a Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands b Department of Public Health & Primary Care, Cardiovascular Epidemiology Unit, University of Cambridge, Cambridge CB1 8RN, United Kingdom c Medical Library, Erasmus MC, Rotterdam, The Netherlands d Department of Respiratory Medicine, Erasmus MC, Rotterdam, The Netherlands e Department of Respiratory Medicine, Ghent University Hospital, 9000 Ghent, Belgium f Leiden University College, The Hague, The Netherlands article info Article history: Received 22 July 2015 Accepted 25 February 2016 Keywords: Lutein Carotenoid Antioxidant Lung function Asthma Systematic review Life course summary 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 caseecontrol 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 respi- ratory health. However, the literature is scarce and most studies are of observational nature. © 2016 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved. 1. Introduction Worldwide, hundreds of millions of people suffer from chronic respiratory diseases encompassing asthma and chronic obstructive pulmonary disease (COPD) [1]. Asthma, a common respiratory disease in childhood and adulthood, has a rapidly increasing prevalence worldwide with a considerably negative impact on the quality of life [2,3]. Many risk factors have been associated with the Abbreviations: BPD, bronchopulmonary dysplasia; COPD, chronic obstructive pulmonary disease; CI, confidence interval; FEV 1 , forced expiratory volume in one second; FVC, forced volume capacity. * Corresponding author. Department of Epidemiology, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands. Tel.: þ31 10 70 43536; fax: þ31 10 7044657. E-mail address: j.c.kiefte-dejong@erasmusmc.nl (J.C. Kiefte-de Jong). 1 Authors contributed equally. Contents lists available at ScienceDirect Clinical Nutrition ESPEN journal homepage: http://www.clinicalnutritionespen.com http://dx.doi.org/10.1016/j.clnesp.2016.02.096 2405-4577/© 2016 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved. Clinical Nutrition ESPEN 13 (2016) e1ee7