Gymnema Sylvestre

Scientific Name(S): Gymnema sylvestre R.Br. It has been referred to in some texts as Asclepias geminata Roxb., Gymnema melicida Edg., and Periploca sylvestris Willd. Family: Asclepiadaceae

Common Name(S): Meshashringi, gurmar, merasingi

Gymnema sylvestre is a member of the milkweed family. It is a woody climbing plant that is native to the tropical regions of India. The leaves are used in herbal medicine preparations and is known as "periploca of the woods" in English. In Sanskrit it is known as mesbasringi (meaning "ram's horn").

Gymnema appears to lower serum glucose and glycosylated hemoglobin (HbA1c) levels following chronic use, but may not have significant acute effects. High-quality human trials are lacking in this area. Some of the available research has been conducted by authors affiliated with manufacturers of gymnema products.

Botany: Gymnema sylvestre is commonly found in Africa and India. Its distribution has become worldwide however, and it is recognized in the traditional medicinal literature of many countries including Australia, Japan and Vietnam. The leaves are most commonly used, but the stem also appears to have some pharmacologic action.

History: Gymnema has played an important role in Ayurvedic medicine for centuries. Its use has been confined primarily to the management of diabetes and similar hypo/hyperglycemic conditions. As early as 1930 the pharmacologic effect of the plant was being investigated. The plant has been used alone and as a component of the Ayurvedic medicinal compound ''Tribang shila," a mixture of tin, lead, zinc, G. sylvestre leaves, neem (Melia azadirachta) leaves, Enicostemma littorale, and jambul (Eugenia jambolana) seeds. The plant also is used in traditional African medicine.

More recently, the plant has been identified by the natural products industry in North America and Europe and a number of commercial over-the-counter herbal products are now available that contain varying amounts of gymnema. These products generally are associated with an ability to control blood glucose levels or to contribute to overall metabolic control.

Uses of Gymnema

The plant has been used in traditional medicine, most notably to control blood glucose.

Side Effects of Gymnema

Gymnema is not known to be toxic, but caution should be exercised as to its hypoglycemic effect. Gymnemic acid inhibits the ability to taste bitterness or sweetness.

Dosage

Clinical trials with diabetics in India have used 400 mg per day of a water-soluble acidic fraction of the gymnema leaves. The gymnemic acid content of this extract is not clear. A recent preliminary trial in the United States reported promising results in a group of type 1 and type 2 diabetics who took 800 mg per day of an extract standardized for 25% gymnemic acids. Traditionally, 2 to 4 grams per day of the leaf powder is used.

Toxicology: Little is known about the safety of this plant. The animal studies that reported the hypoglycemicefficacy of the plant did not provide details of animalsafety. The plant has not been associated with published reports of human toxicity. Because of its documented hypoglycemic effect, it is possible that as few as a dozen tablets of some otc preparations could cause a demonstrable hypoglycemic reaction in humans.

Summary: Gymnema sylvestre is a plant that has found use in the traditional medicine of a number of societies for the management of blood sugar disorders. Pharmacologic evaluations of the plant have found it to possess hypoglycemic activity approximating that of tolbutamide. Little is known about the long-term safety of the plant, but it generally has not been associated with human toxicity. It represents one of a number of plants that should be investigated in more detail for its potential as a hypoglycemic agent.