What is Hibiscus used for?
The hibiscus has had a lengthy history of use in Africa and neighboring tropical countries. Its fragrant flowers have been used in sachets and perfumes. In areas of northern Nigeria, this plant has been used to treat constipation. The fleshy red calyx is used in the preparation of jams, jellies, and cold and warm teas and drinks. The leaves have been used like spinach. The plant is used widely in Egypt for the treatment of cardiac and nerve diseases and has been described as a diuretic. In Iran, drinking sour tea for the treatment of hypertension is a popular practice. It has been used in the treatment of cancers. Research reveals little or no evidence of these medicinal uses of hibiscus. The mucilaginous leaves are used as a topical emollient in Africa. In Western countries, hibiscus flowers are often found as components of herbal tea mixtures. In Thailand, people consume roselle juice to quench their thirst. Karkade seed products (i.e., karkade defatted flour, protein concentrate, protein isolate) have been studied for their nutritional and functional value.
A randomized clinical trial evaluated the effect of sour tea available commercially in Iran on essential hypertension in otherwise healthy volunteers. A decrease in blood pressure was seen. However, after cessation of drinking the sour tea, a rise in blood pressure occurred. Although no adverse effects were seen in this study, the use of sour tea for treating hypertension requires further study.
Aqueous extracts of hibiscus appear to exert a slight antibacterial effect. In laboratory and animal studies, worms were killed by hibiscus extracts. Research reveals little or no clinical data regarding the use of hibiscus as an antibacterial or vermifuge (kill worms).
Components of hibiscus have shown potential as a chemopreventative agent against tumor promotion in laboratory and animal studies. These components also possess anti-inflammatory properties. Research reveals little or no clinical data regarding the use of hibiscus as a chemopreventive agent.
The plant has been used as a mild laxative. While animal studies show a mild cathartic effect, research reveals little or no human clinical data regarding the use of hibiscus as a laxative.
Hibiscus has been studied for its use in preventing renal stone formation, as well as its respiratory and sedative effects. To date there is no clinical evidence to prove any of these beneficial medical effects. Additionally, hibiscus anthocyanins have shown antioxidant activity in protecting against hepatotoxicity in rats. Application and action in humans has yet to be investigated.
What is the dosage of Hibiscus?
There is no clinical evidence on which dosage recommendations can be based. Roselle has generally recognized as safe (GRAS) status as a food. A typical dose as a tea is 1.5g.