Stevia is a genus of 150 species of herbs of the sunflower family (Astereacea). In Malaysia, it is also known as Sugar Tree, as it is believed to reduce diabetes. A stevia type that is widely used as a sweetener is from Rebaudiana species. It is also known as sweetleaf, sugarleaf or sweetherb.
It is a herbaceous plant with soft stem. To plant, the medium used is porous so that no water will stagnate after being watered. It requires enough water and need to be watered 2 times a day in hot weather. It will quickly dry up and die if the water is not enough. The leaves are oval shaped. The bark is smoot. In the optimum level, Stevia can reach a height of up to 1 metre or more. It also produces small white flowers just like daisies. This flower will produce seeds when ripe. Reproduction method usually using stem cuttings. Stem cuttings facilitate root growth. Although it can also reproduce using seeds, but seeds germination rate is very low so it is rarely use.
The active ingredient responsible for the sweet taste of stevia known as steviol glycosides which contained stevioside and rebaudioside . It is stable at high temperatures, pH stable and does not stimulate glycemic response, making it more and more popular especially for people who want to limit the consumption of carbohydrates and avoid diabetes. In addition, stevia also found to treat high blood pressure, reduce levels of uric acid and obesity.
Stevia has been used as a natural sweetener by people in Brazil and Paraguay since hundreds of years ago. It was first used by Red Indians Guarani in Paraguay since 1500 years ago. It is used primarily to sweeten their herbal tea. Apart from that it is also used to sweeten their food. They also use Stevia as a medicine mainly to lower high blood pressure, urination and treat burns.
The use of stevia as a sweetener was discovered by Europeans in the 16th century . Since then it was used extensively in Europe until a visit to Asia. However, studies on Stevia only started in the early 19th century when researchers in Brazil heard a story of a stevia leaf can sweeten the bitter fruit and a cup of herbal tea.
The most unique feature about Stevia is that it is a natural sweetener that does not contain calories. In traditional belief, stevia has zero calories, fat, cholesterol, sugar and carbohydrates. Stevia extract is said to be 300 times sweeter than sugar. This feature has attracted the researchers to carry out research on Stevia. Studies on the toxic content found that the main element in stevia, a steviosid is not toxic. It also did not cause cell mutations and might as well does not give any effect on fertility. However there is a conflict of fertility studies associated with Stevia. One study found that it did not give any effect on fertility, while another study found that water extracted from stevia leaves has lower the levels of testosterone and sperm count in male rats when tested.
Brazilian scientists study in 1991 found steviosid is able to lower blood pressure in rats. From these findings, another test done in 2000 . This time the subject is the 106 Chinese ( men and women ) who suffer from high blood pressure. 60 subjects were given capsules containing 250mg steviosid 3 times a day.
Inspection of the subjects performed once a month for one year. After 3 months, systolic and diastolic blood pressure decreased significantly and lasting impact throughout the year.
Resulting from this study, scientists concluded that steviosid taken orally is effective in lowering blood pressure and it may be considered as an alternative or supplement to high blood pressure. A group of scientists tested the hypoglycemic effects of glycoside in the stevia.
They also studied the effects of glucose production to the glycosides , steviol , isosteviol and glukosilsteviol. Steviol found to not produce glucose . Also in 2000, researchers in Denmark have conducted a study which shows hypoglycemic action in vitro done by steviosid and steviol are the result of the ability to both produce insulin through direct action on beta cells.
They concluded that the study found that these compounds may have the potential to be anti-hypoglycemic agents in the treatment of type 2 diabetes mellitus.
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