Nutritional abnormalities and supplementation in chronic obstructive pulmonary disease

The interest in nutrition in the management of chronic obstructive pulmonar y disease (COPD) has increased dramatically during the past two decades. Tr aditionally weight loss was considered to be an inevitable and irreversible component of the terminal progression of the disease process. From this vi ewpoint, it could be argued that nutritional support might actually influen ce the disease adversely by inducing additional metabolic and ventilatory s tress on the respiratory system. Studies demonstrating the disturbed energy balance during weight loss in COPD have, however, challenged this approach . Furthermore, studies taking a more holistic view of COPD, recognizing the irreversible respiratory impairment and the systemic consequences of the d isease, revealed that nutritional depletion contributes to respiratory and peripheral skeletal muscle weakness and to decreased exercise performance, independent of impaired lung function. In some patients, this condition is reversible after protein-energy supplementation. Moreover, recent studies h ave shown that nutritional abnormalities in patients with COPD relate to a disturbed energy balance and to altered regulation of substrate metabolism caused by changes in anabolic and catabolic stimuli. Further characterizati on and unraveling of these pathophysiologic abnormalities may enlarge the p erspective for nutritional intervention, not merely by protein-energy suppl ementation to reverse weight loss, but also by targeted metabolic modulatio n of specific problems in subgroups of COPD patients, through nutritive and non-nutritive actions at either physiologic or pharmacologic doses.