This present study advances our knowledge on the role of lifestyle factors in myopia (short-sightedness), specifically dietary factors. It has been suggested in previous studies that lower zinc status is associated with myopia; however, this article shows no relationship between dietary zinc intake and myopia in U.S. adolescents.
It has been suggested that low zinc levels may contribute to the development of myopia. The aim of the present study is to examine, for the first time in a Western population, the association of total dietary and supplement zinc intake with myopia.
A total of 1095 children/adolescents aged 12 to 19 years who participated in the U.S. National Health and Nutrition Examination Survey from 2007 to 2008 were enrolled in this study. Multivariate logistic regression analysis was performed to examine the relationship between total zinc intake and myopia after adjustment for potential confounders. In addition, the association between total zinc intake and spherical equivalent refractive error was examined in the myopia group through multiple linear regression.
Among study participants, 30% were found to be myopic (≤−1.00 D). Although median total daily zinc intake was lower among myopes (10.8 [10.2] mg/d) than among nonmyopes (11.1 [10.8] mg/d), the difference was not statistically significant (P = .11). In multiple logistic regression analyses, zinc and copper intakes were not significantly associated with myopia after adjustment for age, sex, body mass index, ethnicity, family income, recreational activity, copper intake, and daily energy intake (in kilocalories per day). In multiple linear regression, spherical equivalent refractive error was not associated with total zinc intake in the myopic group after adjustment for confounding factors (P = .13).
In contrast to previous Asian studies, total zinc intake is not associated with the presence of myopia in U.S. adolescents/children.
1Centre for Eye Research Ireland, Environmental Sustainability and Health Institute, Dublin Institute of Technology, Grangegorman, Dublin, Ireland
2School of Mathematical Sciences, College of Sciences and Health, Technological University Dublin, Dublin, Ireland
3Temple Street Children's University Hospital, Dublin, Ireland
4School of Biological and Health Sciences, College of Sciences and Health, Technological University Dublin, Dublin, Ireland
5African Vision Research Institute, University of KwaZulu Natal, Durban, South Africa
Submitted: December 20, 2018
Accepted: May 24, 2019
Funding/Support: This work was supported by a postgraduate scholarship scheme of Technological University Dublin.
Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest.
Author Contributions and Acknowledgments: Conceptualization: NB, IF, JL; Data Curation: NB; Formal Analysis: NB, JSB; Investigation: JSB, IF; Methodology: NB, JSB, DM, JL; Supervision: JSB, IF, JL; Writing – Original Draft: NB; Writing – Review & Editing: NB, JSB, IF, DM, JL.
We thank all individuals at the National Center for Health Statistics of the Centers for Disease Control and Prevention who were responsible for the planning and administrating of the National Health and Nutrition Examination Survey and making the data sets of the National Health and Nutrition Examination Survey available on their website.