Soursop fruit, with its sweet flesh and distinctive flavor, is grown commercially to make juice, candy, sorbet and ice cream.
It's also is purported to have medicinal qualities, with claims across the Internet that soursop extract can slow the spread of cancer or make traditional cancer therapies work better.
Experts warn against using the fruit to treat cancer. While research suggests soursop can fight cancer, it has not been studied in humans. As a result, there is no evidence of its safety or efficacy.
Soursop has been associated with many unsubstantiated claims, says Daniel Kellman, Clinical Director of Naturopathic Medicine at CTCA outside Atlanta.
The long, prickly fruit comes from the graviola tree, an evergreen native to Mexico, the Caribbean, and Central and South America. It's also known as custard apple, guanabana and Brazilian paw paw. Practitioners of herbal medicine use soursop fruit and graviola tree leaves to treat stomach ailments, fever, parasitic infections, hypertension and rheumatism. It's used as a sedative, as well.
But claims of the fruit's anti-cancer properties have attracted the most attention. A study published in the Journal of Medicinal Chemistry in 1997 suggests that soursop compounds tested on breast cancer cells in culture were more effective than chemotherapy in destroying the cells. But, without clinical trials, there is no data to support the claim.
Most studied are soursop's fatty acid derivatives called annonaceous aceteogenins. The predominant acetogenin is annonacin, which, because of its toxicity, likely would not be studied in clinical trials.
When used orally, soursop is classified as likely unsafe, said Kellman, citing two studies. Eating the fruit could lead to movement disorders similar to Parkinson's disease, according to a case-control study in the French West Indies. In addition, a study suggests tea made for the leaves and stems of graviola is associated with neurotoxicity.
In general, some cancer patients use herbal supplements to relieve their symptoms and to treat their cancer. Herbal supplements, though, are not a substitute for mainstream cancer care. What's more, using herbal supplements while undergoing chemotherapy could reduce the efficacy of chemotherapeutic agents due to possible herb-drug interactions.