Protein and amino acid metabolism in COPD: new insights using stable tracer methodology

Older adults with chronic obstructive pulmonary disease (COPD) generally suffer not only from pulmonary symptoms, but also from other physical complaints such as muscle weakness and impaired physical functioning due to loss of muscle mass, among other things. Proteins are important building stones of the body, particularly the muscles. They are made up of amino acids and are constantly being broken down and rebuilt. The daily protein intake through food helps to maintain muscle. This dissertation examines the process of building up and breaking down proteins and the balance between these (the overall build-up or breakdown) as well as the metabolism of individual amino acids in patients with COPD. It is shown that the high-value milk proteins of whey and casein after bolus intake are equally suitable in terms of composition to stimulate the overall build-up of body proteins in patients with COPD with low muscle mass. It is also shown that in patients with COPD who are clinically stable metabolic changes occur in several individual amino acids, a certain range of disturbances being typical of muscle weakness. These results can contribute to the development of nutritional interventions in patients with COPD in order to maintain muscle mass.