Mangosteen is a tropical fruit native to Southeast Asia. It is consumed both as food and medicine. Data from in vitro and animal studies revealed that it has antioxidant, antiinflammatory, and antiproliferative effects against cancer cells. Xanthones, the major components of mangosteen fruit, have been implicated in such effects. It is yet to be studied in humans. However, despite lack of clinical evidence, mangosteen products are marketed to cancer patients as dietary supplements. Cancer patients should use caution before consuming mangosteen products as they can potentially interact with cancer treatments and also affect blood sugar levels.