MEDICINAL PROPERTIES OF Stevia rebaudiana Bert.
In spite of the prominence Stevia has obtained as a calorie free sweetener and flavour enhancer, it contains a variety of constituents besides the steviosides and rebaudiosides. This including the nutrients specified above and a good deal of sterols, triterpenes, flavonoids, tannins, and an extremely rich volatile oil comprising rich proportions of aromatics, aldehyde, monoterpenes and sesquiterpenes. These and other, as yet unidentified constituents probably have some impact on human physiology and may help explain some of the reported therapeutic uses of Stevia. Stevia has medicinal properties, too. If you use a preparation of the actual plant (not Stevioside), then you may experience benefits other than lowering calories. Scientific research has shown it to be beneficial in regulating blood sugar levels, bringing them into normal range. It is also used as a digestive aid. As a skin care product, it has been used to clear blemishes, tighten skin to remove wrinkles, to heal mouth sores and to treat a variety of wounds. It has also been used to treat eczema, seborrhea and dermatitis.
The following plant chemicals are found in Stevia rebaudiana:
Apigenin-4'-o-beta-d-glucoside, austroinulin, avicularin, beta-sitosterol, caffeic acid, campesterol, caryophyllene, centaureidin, chlorogenic acid, chlorophyll, cosmosiin, cynaroside, daucosterol, diterpene glycosides, dulcosides A-B, foeniculin, formic acid, gibberellic acid, gibberellin, indole-3-acetonitrile, isoquercitrin, isosteviol, jhanol, kaempferol-3-o-rhamnoside, kaurene, lupeol, luteolin-7-o-glucoside, polystachoside, quercetin, quercitrin, rebaudioside A-F, scopoletin, sterebin A-H, steviol, steviolbioside, steviolmonoside, stevioside, stevioside a-3, stigmasterol, umbelliferone, xanthophyll
It is probably the presence of the steviosides themselves that has produced dozens of empirical and semi?controlled reports of hypoglycemic action. Paraguayans say that Stevia is helpful for hypoglycemia and diabetes because it nourishes the pancreas and thereby helps to restore normal pancreatic function in semi?controlled clinical reports one also encounters this action. Oviedo, et.al., reported a 35.2% fall in normal blood sugar levels 6?8 hours following the ingestion of a Stevia leaf extract. Other workers have reported similar trends in humans and experimental animals. These kinds of results have led physicians in Paraguay to prescribe Stevia leaf tea in the treatment of diabetes. Similarly, in Brazil, Stevia tea and Stevia capsules are officially approved for sale for the treatment of diabetes. However, it is important to note that Stevia does not lower blood glucose levels in normal subjects. In one study, rats were fed crude extracts of Stevia leaves for 56 days at a rate of 0.5 to 1.0-gram extract per day. Another team of scientists replicated these procedures.
Neither group observed a hypoglycemic action. Other observers have obtained similar negative results. Then there is research in which the findings show trends toward hypoglycemic action, but are inconclusive. In at least one of these studies, alloxan?diabetic rabbits were used. The authors felt the results supported an anti?diabetic action, but the results were transient at best. To date, the experimental research on the effects of Stevia on blood sugar levels in human patients with either diabetes or hypoglycemia is sparse. The general feeling in the scientific community is that the mild acting nature of the plant and its total lack of toxic side effects argue against the need for extensive and expensive research programs. However, many of the anecdotes reporting a definite and significant blood sugar lowering action in diabetics, and a pronounced exhilarating effect in hypoglycaemic, are sound enough to justify considerable experimental work in the area. Perhaps, when this missing piece to the puzzle is supplied, we will then have a better understanding of how Stevia works. Why, for example, many diabetic humans experience a profound lowering of blood sugar levels following the ingestion of several cups of Stevia tea (24?32 oz.) during the course of a 24-hour period?
A good deal of experimental work has been done on the effects of Stevia and stevioside on cardiovascular functioning in man and animals. Some of this work was simply looking for possible toxicity, while some was investigating possible therapeutic action. In neither case have significant properties been found. When any action at all is observed, it is almost always a slight lowering of arterial blood pressure at low and normal doses, changing to a slight rise in arterial pressure at very high doses. The most curious finding is a dose dependent action on heartbeat, with a slight increase appearing at lower doses, changing to a mild decrease at higher doses. In both instance is the result remarkable, and it is extremely doubtful that humans would experience any effect at normal doses. The long-term use of Stevia would probably has a cardiotonic action, that is, would produce a mild strengthening of the heart and vascular system.
The ability of Stevia to inhibit the growth and reproduction of bacteria and other infectious organisms is important in at least two respects. First, it may help explain why users of Stevia?enhanced products report a lower incidence of colds and flues, and second, it has fostered the invention of a number of mouthwash and toothpaste products. Research clearly shows that Streptococcus mutans, Pseudomonas aeruginos, Proteus vulgaris and other microbes do not thrive in the presence of the non?nutritive Stevia constituents. This fact, combined with the naturally sweet flavour of the herb, makes it a suitable ingredient for mouthwashes and for toothpastes. The patent literature contains many applications for these kinds of Stevia?based products. Stevia has even been shown to lower the incidence of dental caries.
Digestive Tonic Action:
In the literature of Brazil, Stevia ranks high among the list of plants used for centuries by the "gauchos" of the southern plains to flavour the bitter medicinal preparations used by that nomadic culture. For example, it was widely used in their "mate." Through much experimentation, these people learned that Stevia made a significant contribution to improved digestion, and that it improved overall gastrointestinal function. Likewise, since its introduction in China, Stevia tea, made from either hot or cold water, is used as a low calorie, sweet? tasting tea, as an appetite stimulant, as a digestive aid, as an aid to weight management, and even for staying young.
Effects on the Skin:
One of the properties of a liquid extract of Stevia that has not yet been investigated experimentally is its apparent ability to help clear up skin problems. The Guarani and other people who have become familiar with Stevia report that it is effective when applied to acne, seborrhea, dermatitis, eczema, etc. Placed directly in cuts and wounds, more rapid healing, without scarring, is observed. (This treatment may sting for a few seconds, but a significant lowering of pain follows this). Smoother skin, softer to the touch is claimed to result from the frequent application of Stevia poultices and extracts. Current FDA labelling regulations are forcing U.S. suppliers to label their Stevia as something other than a sweetener; an appeal to its soothing action on the skin has been the most frequent alternative. Stevia is also known for skin shining and tightening properties, and has found its way in several commercial skin tightening products or anti-wrinkle products.
A 1-year, double-blind, placebo-controlled study of 106 individuals with high blood pressure evaluated the potential benefits of stevia for reducing blood pressure.4 In the treated group, the average blood pressure at the beginning of the study was about 166/102. By the end of the study, this had fallen to 153/90, a substantial if not quite adequate improvement. In contrast, no significant reductions were seen in the placebo group.
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