Wenjing Tang1, Pengcheng Xun2, Cheng Chen3, Liping Lu3, Akshay Sood4, James M Shikany5, Ka Kahe6. 1. Department of Clinical Nutrition, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Nutrition, Shanghai Jiao Tong University School of Medicine, Shanghai, China. 2. Department of Epidemiology and Biostatistics, School of Public Health-Bloomington, Indiana University, Bloomington, IN, USA. 3. Department of Obstetrics and Gynecology and Department of Epidemiology, Columbia University Irving Medical Center, New York, NY, USA. 4. Health Sciences Center, School of Medicine, University of New Mexico, Albuquerque, NM, USA. 5. Division of Preventive Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA. 6. Department of Obstetrics and Gynecology and Department of Epidemiology, Columbia University Irving Medical Center, New York, NY, USA. Electronic address: kk3399@columbia.edu.
Abstract
BACKGROUND: As an essential micronutrient, zinc plays an important role in modulating the immune system. However, data on the association between zinc concentrations and asthma incidence are sparse, especially in adults. METHODS: We prospectively followed up 3682 individuals aged 20-32 years without history of asthma or current asthma at baseline from 1987-1988 to 2015-2016. Zinc concentrations were measured in toenail clippings collected at Exam Year 2 using inductively-coupled-plasma mass spectroscopy. Asthma was diagnosed by a physician and/or reported medication use for asthma control with verification. Cox regression was used to model the association between toenail zinc concentrations and asthma incidence. RESULTS: Over an average of 22.5 years of follow-up, 508 incident cases of asthma were identified. After adjustment for potential confounders, no statistically significant association was found between zinc concentration and asthma incidence (HR = 0.81; 95% CI: 0.62, 1.07; Plinear trend = 0.26). The observed association was not materially modified by sex, body mass index, smoking or atopic status. When stratifying data by race, a significant inverse linear association was found among African Americans (per 1 standard deviation increment in toenail zinc concentrations: HR = 0.86; 95% CI: 0.75, 0.99; Plinear trend = 0.03), but not in Caucasians (HR = 1.07; 95% CI: 0.91, 1.25; Plinear trend = 0.42), though the test for interaction was not statistically significant (Pinteraction = 0.099). CONCLUSIONS: Findings from this prospective cohort study do not support a significant longitudinal association between toenail zinc concentrations and incidence of asthma among American young adults. Future studies are needed to confirm our findings.
BACKGROUND: As an essential micronutrient, zinc plays an important role in modulating the immune system. However, data on the association between zinc concentrations and asthma incidence are sparse, especially in adults. METHODS: We prospectively followed up 3682 individuals aged 20-32 years without history of asthma or current asthma at baseline from 1987-1988 to 2015-2016. Zinc concentrations were measured in toenail clippings collected at Exam Year 2 using inductively-coupled-plasma mass spectroscopy. Asthma was diagnosed by a physician and/or reported medication use for asthma control with verification. Cox regression was used to model the association between toenail zinc concentrations and asthma incidence. RESULTS: Over an average of 22.5 years of follow-up, 508 incident cases of asthma were identified. After adjustment for potential confounders, no statistically significant association was found between zinc concentration and asthma incidence (HR = 0.81; 95% CI: 0.62, 1.07; Plinear trend = 0.26). The observed association was not materially modified by sex, body mass index, smoking or atopic status. When stratifying data by race, a significant inverse linear association was found among African Americans (per 1 standard deviation increment in toenail zinc concentrations: HR = 0.86; 95% CI: 0.75, 0.99; Plinear trend = 0.03), but not in Caucasians (HR = 1.07; 95% CI: 0.91, 1.25; Plinear trend = 0.42), though the test for interaction was not statistically significant (Pinteraction = 0.099). CONCLUSIONS: Findings from this prospective cohort study do not support a significant longitudinal association between toenail zinc concentrations and incidence of asthma among American young adults. Future studies are needed to confirm our findings.
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