A number of laboratory and animal studies suggest that mangosteen has significant anti-inflammatory effects. But controlled trials in humans are limited, and the studies weren't conducted on people who have arthritis.
Also, the safety of mangosteen juice hasn't been studied thoroughly. When used as food, it seems to be well-tolerated, but more study is needed.
So, while some data appears promising and despite the many health claims made by the manufacturers of mangosteen products, there's not enough evidence to determine what role, if any, mangosteen juice has in treating arthritis symptoms.
Mangosteen is a tropical fruit native to Asia. Despite its name, mangosteen is not related to the mango. The mangosteen fruit is the size and shape of a tangerine, with a thick, dark rind and creamy flesh. Mangosteen is marketed as a supplement, both as a juice and in capsule form.