Dietary modification and nutritional supplements for exercise-induced bronchoconstriction: a systematic review and meta-analysis.

OBJECTIVE: Our aim was to evaluate the effects of dietary modification and nutritional supplementation on exercise-induced bronchoconstriction (EIB) and the certainty of evidence for each intervention. METHODS: PubMed, Web of Science, Scopus, and CENTRAL were searched through to 1 August 2026. Randomized parallel-group and crossover trials assessing EIB with an exercise challenge, eucapnic voluntary hyperpnea (EVH), or another indirect bronchial provocation test were included. The primary outcome was the maximum or peak percentage fall in forced expiratory volume in 1 s (FEV1) within 30 min, with fixed-time-point values treated as proxy outcomes. Comparable intervention-specific effects were synthesized, crossover trials were analyzed as paired designs, and Risk of Bias 2 (RoB 2) and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) were applied. RESULTS: A total of 20 studies (22 reports) were included. Low sodium compared with experimentally prescribed high sodium, standard omega-3 fatty acids/fish oil, selected caffeine doses, and PCSO-524 showed potentially favorable signals. However, the evidence was limited by the small sample sizes, proxy outcomes, heterogeneity, risk of bias, missing paired data, or lack of independent replication. Adverse events were inadequately reported. CONCLUSION: Current evidence is insufficient to recommend any nutritional intervention for routine prevention or treatment of EIB. Nutritional approaches should not replace guideline-based assessment or pharmacological management. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD420261485221.