Bromelain is an enzyme that is obtained from the stem of fresh pineapple. Its best known properties are as a digestive aid and as an accelerator in the healing of sprains and sports sprains.
Another very interesting use of this enzyme is its application in respiratory diseases. Bromelain has an antitussive effect in cases of chronic bronchitis and is able to reduce the viscosity of sputum (due to its mucolytic activity), thereby improving the function and lung capacity of those affected. These beneficial effects of bromelain are the result of facilitating the resolution of respiratory congestion, by fluidizing and decreasing bronchial secretions. Its mucolytic activity makes it a very effective remedy for respiratory tract diseases and also for cases of acute sinusitis.
Reference: The Healing Power of Herbs, ISBN 1-55958-700-8