Immune-modulators (e.g. flavonoids) are known to be present in fruits and vegetables. There are also several different proteolytic and hydrolytic enzymes found in fruits most of whom are attributed protective properties. Therefore, 160 trained and untrained runners will consume a mixture of different enzymes and flavonoids (Wobenzym Plus®) or PL 1 (placebo) and effects on changes in inflammation and hemostasiologic parameters will be investigated during and after extreme physical stress (participation in a marathon race). The clinical result of the perturbation of the immune system will be assessed by the Wisconsin Upper Respiratory Symptom Survey (WURSS-24) with regard to symptoms of the upper respiratory tract system.