Pineapple is made up of bromelain, a complex substance that could relieve symptoms of sinusitis (headache and nasal pain).

Bromelain, unlike other enzymes that are broken down in the digestive system, would be partially absorbed by the body and pass into the blood. It would reduce the production of prostaglandins (= substances of unsaturated fatty acids) which are at the origin of inflammation and would have beneficial effects on the immune system. However, the mechanism of action of bromelain remains unclear.

The Green Pharmacy, James A. Duke Ph.D.