Also called graviola, soursop is a large, spiny, green tropical fruit with a sweet flesh that is the basis for several beverages, ice creams and other sweet foods popular in South America. Beyond its usefulness as a food, however, soursop also contains natural compounds with medicinal properties, making it potentially beneficial for your health.
The graviola tree, or Annona muricata, produces the sweet soursop fruit, also called custard apple, paw paw or, in many Spanish-speaking countries, guanabana. The tree reaches a height of 25 or 30 feet and produces large fruit that may reach a length of 12 inches. Although its rind is quite bitter, the fruit's flesh is soft, smooth and sweet, and provides carbohydrate as its major nutrient. Soursop also contains abundant vitamin C and several B vitamins such as thiamin, riboflavin and niacin, along with calcium, phosphorus and a small amount of iron.
Practitioners of herbal medicine recommend the fruit and leaves of the graviola tree to relieve stomach distress, fever, pain and respiratory problems such as cough and asthma, and for many other medical problems. Soursop contains a number of natural substances that have biological activity, according to Memorial Sloan-Kettering Cancer Center. These include fatty compounds called acetogenins, especially one called annonacin, along with other compounds called quinolones, annopentocins and two alkaloids, coreximine and reticuline. Soursop's acetogenins are the compounds that have been most studied, especially for their potential to prevent or slow the growth of cancer. The Cancer Center also says that some compounds in soursop may be naturally antiviral and antiparasitic, and may also suppress inflammation.
Laboratory research supports the potential benefits of soursop as a remedy for disease. In one study, published in "Journal of Ethnopharmacology," an extract of soursop inhibited the growth of Herpes virus in the laboratory. In addition, the Cancer Center summarizes findings that suggest soursop extracts might slow growth of cancer cells or make them more susceptible to anti-cancer drugs. For example, in one study published in 1997 in "Journal of Medicinal Chemistry," compounds from soursop were tested on breast cancer cells in culture and found to be up to 250 times more effective in killing the cells than some chemotherapy drugs. These laboratory studies with soursop are promising, but research with human subjects is needed to confirm its potential usefulness.
The recommended intake of soursop fruit or its extract has not been established. However, one fruit contains about 15 milligrams of annonacin, its most studied component, and one can of commercially prepared soursop nectar provides 36 milligrams. Avoid consuming soursop in excess, however, since large quantities of its alkaloid compounds may cause neurological symptoms similar to Parkinson's disease.