Chronic obstructive pulmonary disease (COPD) is characterized by increased oxidative stress which aggravates airway and systemic inflammation. Previous studies suggested that dietary factors such as ample consumption of antioxidants might have beneficial effects in lung function in COPD patients.

The investigators' primary aim is therefore to investigate prospectively whether a nutritional intervention consisted of diet rich in antioxidants such as fresh fruits and vegetables, would significantly affect lung function decline in COPD patients compared to a free diet.

Methods: This is a 3-year prospective study, incorporating a run-in period of six months and outpatient clinic visits, scheduled every 6 months. Consecutive sampling was used to recruit 120 patients with COPD. At baseline and at each visit all patients were evaluated for respiratory symptoms, dietary habits, medication used and pulmonary function. Patients will be randomized either to a diet based on increased consumption of foods containing antioxidants (fresh fruits and vegetables), intervention group (IG) or, to a free diet, control group (CG).

The investigators hypothesize that the results from the study will suggest that a diet rich in antioxidants may be associated with improvement in lung function in COPD patients. In this respect dietary interventions should be considered in the management of COPD.

Inclusion Criteria:

• Diagnosis of COPD according to the GOLD definition*
• Ability to perform spirometry.

(*Pauwels RA, Buist AS, Calverley PM, et al. Global strategy for the diagnosis, management and prevention of Chronic Obstructive Pulmonary disease. NHLBI/WHO Global initiative for Chronic Obstructive Lung Disease (GOLD). Workshop summary. Am J Respir Crit Care Med 2001; 163(5):1256-1276.)

Exclusion Criteria:

• A history of lung cancer, bronchial asthma or other respiratory disease
• Continuous use of systemic steroids more than 30 days prior was used as exclusion criteria