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; P_{linear 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; P_{linear trend} = 0.03), but not in Caucasians (HR = 1.07; 95% CI: 0.91, 1.25; P_{linear trend} = 0.42), though the test for interaction was not statistically significant (P_interaction = 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.

中文翻译：

---

美国年轻人脚趾甲锌浓度与哮喘发病率之间的关联：CARDIA 研究

 背景

作为一种必需的微量营养素，锌在调节免疫系统方面发挥着重要作用。然而，关于锌浓度与哮喘发病率之间关系的数据很少，特别是在成人中。

 方法

我们对 1987-1988 年至 2015-2016 年基线时无哮喘病史或当前哮喘的 3682 名 20-32 岁个体进行了前瞻性随访。使用电感耦合等离子体质谱法测量第二年考试时收集的脚趾甲剪中的锌浓度。哮喘由医生诊断和/或报告用于控制哮喘的药物使用情况并进行验证。 Cox 回归用于模拟脚趾甲锌浓度与哮喘发病率之间的关联。

 结果

经过平均 22.5 年的随访，发现了 508 例哮喘病例。调整潜在混杂因素后，锌浓度与哮喘发病率之间没有发现统计学上显着的关联（HR = 0.81；95% CI：0.62，1.07； P_线性趋势= 0.26）。观察到的关联并未因性别、体重指数、吸烟或特应性状态而发生重大改变。按种族对数据进行分层时，在非裔美国人中发现了显着的逆线性相关性（趾甲锌浓度每增加 1 个标准差：HR = 0.86；95% CI：0.75, 0.99； P_线性趋势= 0.03），但在白种人中则不然（HR = 1.07；95% CI：0.91, 1.25； P_线性趋势= 0.42），尽管交互作用检验不具有统计显着性（ P_交互作用= 0.099）。

 结论

这项前瞻性队列研究的结果并不支持美国年轻人脚趾甲锌浓度与哮喘发病率之间存在显着的纵向关联。需要未来的研究来证实我们的发现。