Caffeine consumption, C-reactive protein, and changes in pulmonary function parameters in a longitudinal study

This study aimed to investigate the associations of pulmonary function (PF) parameters with caffeine consumption and serum high-sensitivity C-reactive protein (hsCRP) concentrations. In a longitudinal study involving 2319 adults without respiratory diseases, 2-year alterations between baseline and follow-up PF parameters, including the ratio of forced expiratory volume in the first one second (FEV1) to forced vital capacity (FVC), were calculated. Baseline information on caffeinated beverage consumption, serum hsCRP levels, and confounding variables was collected. Multiple linear regression was used for association analysis. Over 2 years, FEV1 and FVC declined by 2.2% (25.4 mL/year) and 1.3% (26.3 mL/year), respectively. After controlling for potential confounders, including the baseline FEV1/FVC ratio, the 2-year decline from baseline to follow-up in the ratio was lowest among participants consuming ≥200 mg/d of caffeine (p < 0.05), particularly among nonsmokers with serum hsCRP levels <1mg/L. In beverage-specific analyses, the consumption of brewed coffee ≥1 serving/d was associated with the lowest reduction in the FEV1/FVC (p < 0.05), and serum hsCRP was found to act as an effect modifier in this association (p = 0.05). These results suggest that caffeine consumption, particularly of brewed coffee, may mitigate aging-related decline in PF, especially in adults with low systemic inflammation.