Roselle flowers, whether fresh or dried contain anthocyanins which are said to promote cardiovascular health.
Roselle is a species of hibiscus native to West Africa. In Iran, it is typically known as sour tea; in English-speaking countries, it is called red sorrel. It is commonly used to make jelly, jam, juice, wine, syrup, gelatin, pudding, cake, ice cream and flavoring. Originally from Angola, it is now cultivated throughout tropical and sub-tropical countries, such as Sudan, Egypt, Thailand, Mexico and China.
There are three types of roselle, identified by their colours - the dark red type has the highest content of anthocyanins, followed by the light red type, while the green type has only traces of the antioxidant pigment or none at all, reported the Journal Of American Science in 2010.
According to Traditional Chinese Medicine (TCM), : The sour roselle flower is cold in nature. This makes it suitable for clearing "heaty" symptoms associated with hot and humid weather, such as a sore throat, a dry mouth, thirst, dry stool and yellowish urine. It is thought that the diuretic effect of roselle flowers helps remove heat from the body.
In traditional Chinese medicine (TCM), excessive consumption of high-calorie food affects the digestive functions of the spleen and stomach, said Madam Cheung. In addition, when there is deficiency of yin (the element responsible for cooling organs) in the kidneys and liver, heat builds up in the body and hinders blood flow.
Poor functioning of these organs causes phlegm and other unwanted substances to accumulate in the body, disrupting the proper circulation of blood and qi. A person with poor qi or blood flow will experience symptoms, such as a red face, heart palpitations, numbness in the limbs, and would get agitated and tired easily.
People with neutral or "heaty" bodies can benefit from taking a "cold" herb, such as roselle flowers, to balance their body constitutions. It is also suitable for those with hypertension and high cholesterol. The latest National Health Survey in 2010 found that 23.5 per cent of Singapore residents had hypertension and 17.4 per cent had high cholesterol. One should consume no more than 3g of roselle flowers a day, said Madam Cheung.
People with a weak stomach and spleen, which is marked by a bloated abdomen, diarrhoea and a poor appetite, should avoid taking cold herbs. The same is true for pregnant women and those having their periods. Taking sour herbs, such as roselle flowers, will also aggravate the symptoms of people with stomach ulcers.
Daily consumption of a tea or extract produced from roselle flowers has benefits for adults, according to a review of human and animal studies published in the journal for the study of medicinal plants, Fitoterapia, in March 2013. Specifically, it helped to significantly lower one's systolic and diastolic blood pressure in people with pre- to moderate primary hypertension and type 2 diabetes, based on results from randomised controlled trials.
In addition, the tea was as effective at lowering blood pressure as the drug Captropril, but less effective than another drug, Lisinopril. Both drugs are used to treat high blood pressure. More than half of the trials showed that daily consumption of roselle tea or extracts improved one's lipid levels.
Namely, it lowered participants' levels of total cholesterol, low-density lipoprotein or "bad" cholesterol, and triglycerides. At the same time, it boosted their levels of high-density lipoprotein or "good" cholesterol. The observations were likely a result of the antioxidant effects of the anthocyanins. These compounds inhibit the oxidation of "bad" cholesterol, hence impeding the development of atherosclerosis (hardening of the arteries), which can lead to cardiovascular disease.
* Read on via Asia One: Your Health.