Karkade - Roselle

Detailed Description

A beverage cherished across cultures, with both traditional uses and scientific evidence supporting its benefits.

Botanical Information

The Hibiscus genus consists of numerous species, exhibiting incredible diversity in their botanical form. These include herbs, shrubs, subshrubs, and even trees, which may be either deciduous or evergreen. All hibiscus plants have alternately arranged leaves, which can be lobed, oval, lanceolate, or simple, featuring palmate venation. Karkade flowers are large and striking, with calyx-shaped to bell-shaped blooms. Hibiscus typically displays an exemplary, entire flower composed of five or more petals ranging from white to red hues, often with various color combinations or gradations that may change as the plant matures. Karkade flowers are regular, symmetrical, and bisexual. The fruit is a capsule made up of five separate compartments, each containing several seeds that are released as the capsule dries.

Origin and Distribution

Hibiscus is widespread globally, and roselle is common in temperate, subtropical, and tropical zones. It also thrives in Central Europe, such as in the southern regions of the Czech Republic.

Usage / Dosage

Research on tissue cultures has shown that roselle, or any hibiscus flower tea, can reduce blood pressure in people with type 2 diabetes, those with mildly elevated blood pressure, and those with hypertension. It is not yet considered a standalone treatment for these conditions, but its effectiveness in lowering blood pressure is notable compared to other plants with similar effects. For instance, a study observed an average decrease of about 15 mmHg in systolic blood pressure after drinking karkade three times a day for six weeks among diabetics and hypertensive individuals. This effect is attributed to anthocyanins, particularly hibiscin, delphinidin, cyanidin, hibiscretin, and their derivatives, which are believed to work similarly to ACE inhibitors (angiotensin-converting enzyme inhibitors). As a result, several studies have compared the antihypertensive effect of hibiscus tea to captopril, finding high safety and tolerance levels.

In addition to cardiovascular benefits, roselle is linked to a reduction of venous resistance in the lower limbs. The anthocyanins that lower arterial pressure may also relieve heavy legs and swelling. Hibiscus tea contains glycosidic derivatives with a diuretic (water-reducing) effect, which not only lowers blood pressure but also increases venous return and diminishes lower limb swelling.

Among patients with high blood pressure and elevated blood lipids, regular consumption of hibiscus tea has been observed to lower LDL cholesterol and free fatty acids in the blood, particularly when consumed twice daily for several months. These results partially support the traditional use of roselle for weight management and appetite control.

Both animal and human studies have demonstrated the significant antioxidant and anti-inflammatory effects (acting as a natural disinfectant). Hibiscus seeds are rich in anti-inflammatory compounds, including tocopherol (vitamin E) and omega fatty acids. These substances are also present in the flowers and the tea, though in smaller amounts—the infusion process results in more vitamin C (water-soluble), while less tocopherol (fat-soluble) is present. In general, roselle supports the body's natural defenses and enhances the immune system in fighting both internal and external pathogens.

An interesting finding in studies of hibiscus flower infusions (karkade) is their potential use among middle-aged and older men for dissolving urinary tract stones, through increased excretion of creatinine, uric acid, citrates, tartrates, and alkaline metals. Roselle is also valued for its diuretic properties.

Traditionally, karkade is enjoyed both in summer (refreshing when cold) and in winter (warming when hot). It is used in traditional medicine for lowering elevated body temperature and is recommended for fevers. The compounds in roselle are also believed to reduce muscle cramps and are advised for fever accompanied by febrile convulsions. Studies suggest these compounds positively affect intestinal motility, making karkade useful for digestive complaints and appetite issues.

Roselle may support central nervous system function by boosting and optimizing brain cell metabolism, improving the use of glucose and some fats as energy sources for nerve tissue. It is believed to enhance both attention and memory capacity and stimulate mental activity. Traditionally, karkade is recommended for chronic fatigue. Drinking roselle is also associated with increased well-being, relaxation, and body rejuvenation. In cultures where karkade is commonly consumed, it is believed to promote overall physical and mental vitality.

In traditional Indian (Ayurvedic) medicine, both the root and flower of hibiscus (in decoction) have been used for cough relief, hair loss, and preventing premature graying. In India, hibiscus flowers and leaves are combined and the extract made into a paste for use as a hair conditioner.

Active Compounds

Roselle tea is rich in minerals and antioxidants, including ascorbic acid (vitamin C) and, in smaller amounts, some fat-soluble nutrients. Key compounds include anthocyanins such as cyanidin and delphinidin glycosides, polyphenols with astringent and anti-diarrheal activities (and suspected anti-cancer effects for the liver and brain), essential amino acids, and flavonoid glycosides. Flavonoids are responsible both for some of the beneficial effects and the deep red color of both the hibiscus flower and the resulting infusion.

Traditional Dosage

Fresh hibiscus flowers should be steeped in approximately 95°C hot water for 5–10 minutes. The suggested amount is about 1 tablespoon of flowers per 500 ml of water. Strain before consuming; sweeten with honey or sugar, or add spices as desired. The resulting brew is deep red, reminiscent of a cup of blood. In some cultures, karkade is often enjoyed with ginger. It can be served either hot or cold. An interesting fact: when karkade tea is poured into cold water, it turns blue.