The rose apple is used as food and as medicine. You'll find the rose apple plant, technically called Syzygium jambos, in tropical and subtropical areas where a mature tree will yield 5 lbs. fruit each season. The fruit on this plant does not actually resemble an apple --- the plant is a member of the myrtle family, according to Indiana's Purdue University. If you plan to use rose apple for medicinal purposes consult a health care provider first.
Rose-apples are a popular fruit among children in tropical areas, according to Purdue University. The fruits provide thiamin, vitamin C, calcium, magnesium, iron, potassium and sulfur. The rose apple also is a source of fiber and is low in fat and calories, with 56 calories per 100g of the edible portion of the plant.
The rose apple is used for multiple purposes in traditional medicine. People in sub-Saharan Africa use the rose apple bark to treat infectious diseases, says C.D. Djippa, lead author for a study published in the "Journal of Ethnopharmacology."
A rose apple fruit infusion may work as a diuretic, according to Purdue University. Rose apple seeds also are used to halt diarrhea, according to P. K. Warrier, lead author for "Indian Medicinal Plants." In India, the fruit is used as a liver tonic and a brain tonic. Preparations of the flowers also are used as fever-reducers. In Cuba, people believe the rose apple root is an epilepsy remedy. In Nicaragua, infusions of roasted and powdered seeds are used to benefit diabetics.
In Ayurvedic medicine, a dried mixture of rose apple vinegar and iron dust is used as a general tonic, a liver tonic and a blood tonic, according to the "Handbook on Ayurvedic Medicines," by H. Panda.
Science to back up traditional uses is scanty, but some beneficial properties have been identified. The high tannin content of rose apple bark extract gives it antibiotic properties that may be useful for fighting staph infections --- at least in lab tests, according to Djippa.
J.R. Kuiate, lead author for a study published in "Phytotherapy Research," also found in lab studies that the plant's stem bark may be useful for fighting some skin diseases. The bark's active compounds, betulinic acid and friedelolactone, are active against fungal infections on the skin that are common in Camaroon, Kuiate notes.
The alkaloid called jambosine, found in the tree trunk and root bark, is theorized to lower blood-glucose levels, which may be helpful with diabetes. Jambosine stops the conversion of starch into sugar. However, a 12-day study on jaman fruit extract, which also contains this alkaloid, found insignificant effects, says Mahpara Safdar, lead author for a study published in the "Pakistan Journal of Nutrition." Safdar notes the results are inconclusive, however, due to the short time frame of the study as well as the preservatives used in the extract.
You need to be careful in using rose apple preparations due to toxicity risk, advise the experts at Purdue. The rose apple's seeds are poisonous, as are its roots. There's an unknown amount of hydrocyanic acid, also called prussic acid or cyanide, in the plant's stems, roots and leaves. Hydrocyanic acid poisoning can be fatal.
If nothing else, you can use rose apple to make perfume, note Jules Janick and Robert E. Paull in "The Encyclopedia of Fruits and Nuts." The essential oil extracted from rose apple's leaves is used for this purpose. The tree's hardwood also is useful in construction, and the bark can be used for tanning and dyeing.