Researchers assessed dietary caffeine using up to two 24-hour dietary recalls for each participant. They expressed caffeine intake in milligrams per 1,000 kilocalories to account for energy intake, then logarithmically transformed these values for continuous analyses. Current asthma was determined from responses to a standardized NHANES respiratory questionnaire. The investigators used survey-weighted logistic regression models to estimate associations between caffeine intake and current asthma, with adjustment for potential confounders. They also conducted restricted cubic spline analyses to assess the relationship across the range of caffeine intake.

Results from the fully adjusted model did not show a statistically significant association. For each one-unit increase in log-transformed, energy-adjusted caffeine intake, the adjusted odds ratio for current asthma was 0.95, with a 95% confidence interval of 0.89–1.02 and a P value of 0.141. The confidence interval included 1.00, meaning the result did not meet the threshold for statistical significance; it does not establish the absence of any association or rule out a modest effect. The authors also cautioned that limited exposure variability and the width of the confidence intervals prevented a definitive exclusion of a small association.

Categorical analyses produced the same overall interpretation. Compared with participants who did not consume caffeine, adjusted odds ratios for current asthma across increasing caffeine-intake tertiles were 1.13 in the lowest tertile, 0.91 in the middle tertile and 0.87 in the highest tertile. Their respective 95% confidence intervals were 0.80–1.59, 0.69–1.20 and 0.67–1.12. The P value for trend was 0.113, indicating that the estimates did not demonstrate a statistically significant pattern across intake categories. Restricted cubic spline analyses likewise found no significant overall or nonlinear association.

Sensitivity analyses did not materially change the findings. Analyses incorporating multiple imputation, additional adjustment for dietary variables and adjustment for NHANES survey cycle yielded results similar to the main analysis. The study’s scope was limited to the measured dietary exposure and current asthma status among the 8,812 participants included in NHANES 2011–2020. Because it was an observational cross-sectional analysis based on de-identified survey data, it involved neither an intervention nor prospective assignment of participants. The authors called for prospective studies with repeated exposure assessments and objective asthma measurements, noting that a modest association cannot be excluded from the present results. The defensible conclusion is that estimated dietary caffeine intake was not significantly associated with current asthma in this population, not that caffeine has no effect on childhood asthma.

Subject of Research: Association between dietary caffeine intake and current asthma in U.S. children and adolescents

Article Title: Dietary caffeine intake and current asthma among U.S. children and adolescents: a cross-sectional study based on NHANES 2011–2020

Article References: Zhang, M., Zhang, Y., Tian, Y., Zhang, X., Chen, Y., Zhang, C., Han, S., Ren, X., & Liu, R. (2026). Dietary caffeine intake and current asthma among U.S. children and adolescents: a cross-sectional study based on NHANES 2011–2020. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07601-z

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07601-z

Keywords: childhood asthma, adolescent health, dietary caffeine, NHANES, cross-sectional study, dietary recalls, odds ratios, pediatric epidemiology, Dietary, caffeine, intake, current