Antioxidant defence responses in chronic obstructive pulmonary disease: Association with disease severity and effects of nutritional intervention

Abstract

Chronic Obstructive Pulmonary Disease (COPD) is characterised by persistent airflow limitation and systemic inflammation, with oxidative stress increasingly recognised as a central pathogenic mechanism. This research investigated the relationship between antioxidant defence capacity and disease severity in COPD patients, and evaluated the efficacy of antioxidant supplementation in improving oxidative status. The investigation was conducted at the Instituto Colombiano de Investigación Respiratoria, Medellín, Colombia, between May 2020 and December 2021, comprising a cross-sectional observational phase followed by a randomised controlled intervention trial. The observational phase enrolled 100 COPD patients stratified by GOLD severity criteria (mild n=25, moderate n=38, severe n=37) and 25 age-matched healthy controls. The intervention phase randomised 60 moderate-severe COPD patients to placebo, low-dose (vitamin C 500mg + vitamin E 200IU daily), or high-dose (vitamin C 1000mg + vitamin E 400IU daily) antioxidant supplementation for 12 weeks. Blood samples were analysed for Superoxide Dismutase (SOD), Catalase (CAT), glutathione peroxidase (GPx), Total Antioxidant Capacity (TAC), and Malondialdehyde (MDA). Antioxidant enzyme activities declined progressively with increasing COPD severity: SOD decreased from 1842 ± 156 U/g Hb in controls to 1187 ± 118 U/g Hb in severe COPD (p