Analysis of 12,400 Korean adults reveals that pro-inflammatory diets—measured by the energy-adjusted Dietary Inflammatory Index across 21 food parameters—significantly correlate with higher asthma prevalence and reduced lung function. Most striking was the differential impact: inflammatory diets decreased predicted lung capacity (FEV1) four times more severely in asthma patients (beta = -0.613) compared to healthy individuals (beta = -0.147), suggesting pre-existing airway inflammation amplifies dietary damage. This finding extends beyond previous Western research by documenting these associations in an Asian population with distinct dietary patterns and genetic backgrounds. The implications are substantial for respiratory health management—anti-inflammatory dietary interventions could offer therapeutic benefits, particularly for asthma patients who appear uniquely vulnerable to inflammatory foods. However, this cross-sectional design cannot establish causation, and the 24-hour dietary recall may not capture long-term patterns. As a preprint awaiting peer review, these results require validation through replication studies and potentially randomized controlled trials testing whether anti-inflammatory diets actually improve lung function outcomes in real-world settings.