That an enzyme, bromelain, found in the juice and stem of the pineapple plant, may reduce inflammation associated with asthma. Pineapple is also an excellent source of vitamin C, an important antioxidant that may help asthmatics. Asthma suffers have lower serum levels of vitamin C than people without this condition, according to a study conducted by the Centers for disease Control and Prevention. You can also up your intake of C by eating a variety of citrus fruits or taking a supplement..