The correlation between selenium intake and lung function in asthmatic people: a cross-sectional study

Abstract

Objective: This study aimed to examine the correlation between selenium intake and lung function in asthmatic people.

Methods: A total of 4,541 individuals in the US National Health and Nutrition Examination Survey (NHANES) were included in this study. Multivariate linear regression, variance inflation factor, restricted cubic splines and quantile regression were used to analyze the relationship between Se intake and lung function. We divided selenium intake into four levels based on quartiles: Q1: Se ≤ 76.75 mcg/d; Q2: 76.75-105.1 mcg/d; Q3: 105.1-137.65 mcg/d; and Q4: Se ≥137.65 mcg/d.

Results: Asthma was negatively associated with the Ratio of Forced Expiratory Volume 1st Second to Forced Vital Capacity (FEV1/FVC) (β = -0.04, 95% CI: -0.06 to -0.02) and FEV1 (β = -215, 95% CI: -340 to -90). Se intake was positively associated with Forced Expiratory Volume 1st Second (FEV1) (β =3.30 95% CI: 2.60 to 4.00) and Forced Vital Capacity (FVC) (β =4.30, 95% CI: 3.50 to 5.10). In asthmatic individuals, the positive effects of Se intake on FVC were enhanced with increasing Se intake, while the positive effects of Se intake on FEV1 varied less dramatically. High Se intake (Q4 level, above 137.65 mcg/d) improved FVC (β = 353, 95% CI: 80 to 626) and FEV1 (β = 543, 95% CI: 118 to 969) in asthmatic patients compared to low Se intake (Q1 level, below 76.75 mcg/d). At the Q2 level (76.75-105.1 mcg/d) and Q4 level (Se ≥137.65 mcg/d) of Se intake, the correlation between FEV1 and asthma disappeared.

Conclusion: Our research has revealed a positive correlation between selenium intake and lung function in asthma patients and the strength of this positive correlation is related to the amount of selenium intake. We recommend that asthma patients consume 137.65 mcg to 200 mcg of selenium daily to improve pulmonary function while avoiding the adverse effects of selenium on the human body.

Keywords: NHANES (National Health and nutrition examination survey); asthma; cross-sectional study; lung function; selenium intake.

Figure 1

Flowchart of the sample selection from NHANES 2007–2012.

Figure 2

The distributions of lung function in different combinations of asthma and Se intake.

Figure 3

Restricted cubic spline of the association of asthma and lung function. (A) Asthma− and FEV1/FVC; (B) Asthma− and FEV1; (C) Asthma− and FVC; (D) Asthma+ and FEV1/FVC; (E) Asthma+ and FEV1; (F) Asthma+ and FVC; Red line and blue transparent area represent smooth curve fit and 95% CI fit, respectively. Adjusted for age, sex, race, PIR, education levels, triglycerides, smoking status, BMI, ASBP, ADBP, urinary creatinine, high-density cholesterol (HDL), and hemoglobin.

Figure 4

Decimal quantile regression of the association of asthma and lung function. (A) Asthma+ and FEV1/FVC; (B) Asthma+ and FEV1; (C) Asthma+ and FVC; Black line and gray transparent area represent smooth curve fit and 95% CI fit, respectively. Adjusted for age, sex, race, PIR, education levels, triglycerides, smoking status, BMI, ASBP, ADBP, urinary creatinine, high-density cholesterol (HDL), and hemoglobin.

Figure 5

Associations between lung function and Se (divided into Q1, Q2, Q3 and Q4 according to quartiles, Q1: Se ≤ 76.75 mcg/d; Q2: 76.75–105.1 mcg/d; Q3: 105.1–137.65 mcg/d; Q4: Se ≥137.65 mcg/d). Adjusted for age, sex, race, PIR, education levels, triglycerides, smoking status, BMI, ASBP, ADBP, urinary creatinine, high-density cholesterol (HDL), and hemoglobin.

Figure 6

Stratified analysis of associations between asthma and lung function according to the quartiles of Se (divided into Q1, Q2, Q3 and Q4 according to quartiles, Q1: Se ≤ 76.75 mg; Q2: 76.75–105.1 mg; Q3: 105.1–137.65 mg; Q4: Se ≥137.65 mg). Adjusted for age, sex, race, PIR, education levels, triglycerides, smoking status, BMI, ASBP, ADBP, urinary creatinine, high-density cholesterol (HDL), and hemoglobin.