The high antioxidant content of passion fruit peels may give them powerful anti-inflammatory effects when they're taken as a supplement.
One small study investigated the effects of a purple passion fruit peel supplement on symptoms of asthma over four weeks (21).
The group who took the supplement experienced a reduction in wheezing, coughing and shortness of breath.
However, this was a very small study, so further research is required before it's known if this therapy is helpful for those with asthma.
Other research has examined the effects of purple passion fruit peel extract on joint pain and function in people with knee osteoarthritis. This is a painful condition caused by inflammation in the knee joint (22).
The researchers found that people who took the supplement reported less pain and stiffness in their joints than those who didn't.
Overall, the effects of antioxidants on inflammation and pain in osteoarthritis are still unclear and more research is needed.