Many people associate hibiscus with its beautiful flowers but it is also used around the world in herbal remedies, primarily as a tea.
The hibiscus associated with health benefits and popularly served in a tea infusion is botanically known as Hibiscus sabdariffa L. It is also known by the common name roselle. This shrub has yellow flowers with a red centre and the flowers, fruit and especially the calyx (the bowl-shaped structure that supports the flower) are used to make hibiscus tea, which is known as sour tea in Iran. It is a popular beverage in many countries, including Egypt, Sudan and Germany.
What benefits are associated with taking hibiscus?
Claims have been made that hibiscus can help to lower blood pressure. According to a study published by Phytomedicine in 2004, patients with hypertension and a control group were given either an infusion prepared with Hibiscus sabdariffa L. for a month or captopril (a medicine used to treat high blood pressure). The study, which had 75 participants, indicated that drinking hibiscus tea could decrease blood pressure.
Another study, published in the Journal of Human Hypertension in 2009, compared the effect of drinking hibiscus tea with black tea in 60 diabetic patients with mild hypertension. The study concluded that drinking hibiscus tea had positive effects on blood pressure in type 2 diabetic patients with mild hypertension.
In another study, published in the Journal of Nutritionin 2010 and presented by the American Heart Association, 65 pre and mildly hypertensive adults were given either 240ml of hibiscus tea three times a day or a placebo for 6 weeks. Although there was no significant difference in the diastolic blood pressure between the group drinking the hibiscus tea and the control group, the study found that hibiscus tea lowered systolic blood pressure.
However, these are all small studies and more research is needed to substantiate these claims.
Health claims have been made that Hibiscus sabdariffa L. in infusion form can bring about an improvement of diuretic function and bowel motor function, but the European Food Safety Authority (EFSA) has found there is no evidence to substantiate this.
Hibiscus tea is traditionally used in some countries for a range of symptoms such as treating a sore throat or cough and reducing restlessness. As an emollient made from leaves it is used for treating skin wounds. However there is no scientific research indicating that hibiscus is effective in these treatments.
How is hibiscus consumed?
The dried calyxes are used to make a tea. It is used commercially in a number of herbal tea blends and to flavour other beverages. The prepared fruits are cooked as a side dish in African countries and they are used to make sauces, jams and chutneys. The young leaves can be added to salads.
Are there any risks associated with hibiscus?
If you are allergic or sensitive to members of the Malvaceae plant family, you should avoid consuming beverages or foods prepared with hibiscus. As little is known about its safety, it is best to avoid hibiscus if you are pregnant or breastfeeding.
The MHRA, the agency responsible for regulating all medicines and medical devices in the UK, has received four reports of possible adverse effects associated with the ingestion of hibiscus, with two cases being linked to digestive problems and to liver problems.