Systemic Inflammation in Chronic Obstructive Pulmonary Disease: May Diet Play a Therapeutic Role?

Chronic obstructive pulmonary disease (COPD) is a significant and rising global health problem. It is a complex disease with genetic, epigenetic, and environmental influences characterized by progressive airflow limitation, chronic inflammation in the lungs, and associated systemic inflammation. No effective cure for COPD exists to date and research into new therapies will be essential if this disease is to be managed in the future. Obesity with the metabolic syndrome and malnutrition represent two poles of metabolic abnormalities that may relate to systemic inflammation. The metabolic syndrome is present in almost 50% of COPD patients. Instead, peripheral skeletal muscle dysfunction is an established systemic feature of COPD. Malnutrition varies from 20% to 50% in patients with COPD. Reduction in body weight by more than 10% of the ideal weight is an independent negative prognostic factor in COPD. We assume that in patients with COPD and concurrent alteration of nutritional status at least three factors play a role in the systemic inflammatory syndrome: the severity of pulmonary impairment, the degree of obesityrelated adipose tissue hypoxia, and the severity of systemic hypoxia due to reduced pulmonary functions. Further research should elucidate the complex relationship between obstructive lung disease and systemic inflammation and oxidant stress, as well as the role of systemic inflammation in coexisting conditions, such as obesity and malnutrition. In this scenario, diet is a modifiable risk factor for COPD that appears to be more than an option to prevent and modify the course of COPD. Mounting evidence from human studies and experimental investigations have shed new light on the relationship between diet, lung function and COPD development, showing protective or harmful role of certain foods, nutrients and dietary patterns on pulmonary function and COPD development. In particular, beneficial effects on lung function and COPD development have been described for dietary antioxidants including vitamins and polyphenols, mainly from fresh fruits and vegetables, n-3 polyunsaturated fatty acids (PUFA) as well as dietary patterns rich in these constituents, possibly through antioxidant and anti-inflammatory mechanisms. A better understanding of dietary influences on COPD will hopefully lead to design more effective and personalized approach for the nutritional prevention and treatment of this disabling condition.