Gymnema sylvestre is a plant used medicinally in India and Southeast Asia for treatment of “sweet urine” or what we refer to in the West as diabetes or hyperglycemia. In ancient Indian (Ayurvedic medicine) texts, gymnema is referred to as gurmar, which means “sugar destroyer” in Sanskrit. Gymnema leaves, whether extracted or infused into a tea, suppress glucose absorption and reduce the sensation of sweetness in foods – effects which may deliver important health benefits for individuals who want to reduce blood sugar levels or body weight. Modern-day dietary supplements containing gymnema are typically intended for control of blood sugar and insulin levels, reduction of sugar cravings, and weight loss – particularly in patients with diabetes.
As a dietary supplement to enhance control of blood glucose and insulin, gymnema sylvestre appears to be effective – particularly in the case of individuals with diabetes or hyperglycemia (elevated blood sugar). As an agent to promote weight loss, gymnema may help control appetite and carbohydrate cravings – effects which may be helpful in some individuals attempting weight loss.
Gymnema sylvestre leaves contain gymnemic acids, which are known to suppress transport of glucose from the intestine into the blood stream and a small protein, gurmar, that can interact with receptors on the tongue to decrease the sensation of sweetness in many foods (Miyasaka and Imoto 1995). This dual action has been shown to reduce blood sugar and cholesterol levels in diabetic animals and humans and may provide some benefits in terms of regulating appetite control and food cravings (Suttisri et al. 1995).
The hypoglycemic effect of gymnema has been known for centuries. Modern scientific methods have isolated at least nine different fractions of gymnemic acids which possess hypoglycemic activity (Chattopadhyay 1998, Fushiki et al. 1992). The effect of gymnema extract on lowering blood levels of glucose, cholesterol and triglycerides is fairly gradual – typically taking a few days to several weeks. Very high doses of the dried gymnema leaves may even help to repair the cellular damage that causes diabetes by helping to regenerate the insulin producing beta-cells in the pancreas (Shanmugasundaram et al. 1990).
Several human studies conducted on gymnema for treatment of diabetes have shown significant reduction in blood glucose, glycosylated hemoglobin (an index of blood sugar control) and insulin requirements (Baskaran et al. 1990, Khare et al. 1983). Gymnema appears to increase the effectiveness of insulin rather than causing the body to produce more (Shanmugasundaram et al. 1981) – although the precise mechanism by which this occurs remains unknown. As with other natural ingredients for control of blood sugar and insulin levels, such as banaba leaf, a common “side effect” is weight loss (Khare et al. 1983) – probably due to a combination of appetite suppression and control of food cravings (especially for carbohydrates and sweets).
At typical recommended doses (see below), dietary supplements containing gymnema are not associated with significant adverse side effects. Mild gastrointestinal upset may occur if gymnema is taken on an empty stomach – so consumption with meals is recommended. Caution is urged, however, because of the potential to induce hypoglycemia in susceptible individuals. In those individuals with active diabetes, it is recommended to consult your personal physician before and during use of gymnema, as alterations to your dosage of insulin or other anti-diabetic medications may be warranted. Certain medications, including antidepressants (St. John’s wort) and salicylates (white willow and aspirin) can enhance the blood sugar-lowering effects of gymnema, whereas certain stimulants such as ephedra (Ma Huang) may reduce its effectiveness. Most human studies have been conducted in diabetic patients and have used 400-600mg of gymnema extract per day in conjunction with conventional oral anti-diabetic medications to lower blood glucose and reduce insulin requirements. In non-diabetics, smaller doses may be effective in helping to control blood sugar and insulin fluctuations – and the associated swings in appetite and food cravings. Because it acts gradually, gymnema extract should be consumed regularly with meals for several days/weeks.
1.Baskaran K, Kizar Ahamath B, Radha Shanmugasundaram K, Shanmugasundaram ER. Antidiabetic effect of a leaf extract from Gymnema sylvestre in non-insulin-dependent diabetes mellitus patients. J Ethnopharmacol. 1990 Oct;30(3):295-300.
2.Chattopadhyay RR. Possible mechanism of antihyperglycemic effect of Gymnema sylvestre leaf extract. Gen Pharmacol. 1998 Sep;31(3):495-6.
3.Fushiki T, Kojima A, Imoto T, Inoue K, Sugimoto E. An extract of Gymnema sylvestre leaves and purified gymnemic acid inhibits glucose-stimulated gastric inhibitory peptide secretion in rats. J Nutr. 1992 Dec;122(12):2367-73.
4.Khare AK, Tondon RN, Tewari JP. Hypoglycaemic activity of an indigenous drug (Gymnema sylvestre, 'Gurmar') in normal and diabetic persons. Indian J Physiol Pharmacol. 1983 Jul-Sep;27(3):257-8.
5.Miyasaka A, Imoto T. Electrophysiological characterization of the inhibitory effect of a novel peptide gurmarin on the sweet taste response in rats. Brain Res. 1995 Apr 3;676(1):63-8.
6.Murakami N, Murakami T, Kadoya M, Matsuda H, Yamahara J, Yoshikawa M. New hypoglycemic constituents in "gymnemic acid" from Gymnema sylvestre. Chem Pharm Bull (Tokyo). 1996 Feb;44(2):469-71.
7.Ota M, Shimizu Y, Tonosaki K, Ariyoshi Y. Role of hydrophobic amino acids in gurmarin, a sweetness-suppressing polypeptide. Biopolymers. 1998 Mar;45(3):231-8.
8.Shanmugasundaram ER, Gopinath KL, Radha Shanmugasundaram K, Rajendran VM. Possible regeneration of the islets of Langerhans in streptozotocin-diabetic rats given Gymnema sylvestre leaf extracts. J Ethnopharmacol. 1990 Oct;30(3):265-79.
9.Shanmugasundaram ER, Rajeswari G, Baskaran K, Rajesh Kumar BR, Radha Shanmugasundaram K, Kizar Ahmath B. Use of Gymnema sylvestre leaf extract in the control of blood glucose in insulin-dependent diabetes mellitus. J Ethnopharmacol. 1990 Oct;30(3):281-94.
10.Shanmugasundaram KR, Panneerselvam C, Samudram P, Shanmugasundaram ER. The insulinotropic activity of Gymnema sylvestre, R. Br. An Indian medical herb used in controlling diabetes mellitus. Pharmacol Res Commun. 1981 May;13(5):475-86.
11.Shimizu K, Abe T, Nakajyo S, Urakawa N, Atsuchi M, Yamashita C. Inhibitory effects of glucose utilization by gymnema acids in the guinea-pig ileal longitudinal muscle. J Smooth Muscle Res. 1996 Oct;32(5):219-28.
12.Shimizu K, Iino A, Nakajima J, Tanaka K, Nakajyo S, Urakawa N, Atsuchi M, Wada T, Yamashita C. Suppression of glucose absorption by some fractions extracted from Gymnema sylvestre leaves. J Vet Med Sci. 1997 Apr;59(4):245-51.
13.Shimizu K, Ozeki M, Tanaka K, Itoh K, Nakajyo S, Urakawa N, Atsuchi M. Suppression of glucose absorption by extracts from the leaves of Gymnema inodorum. J Vet Med Sci. 1997 Sep;59(9):753-7.
14.Suttisri R, Lee IS, Kinghorn AD. Plant-derived triterpenoid sweetness inhibitors. J Ethnopharmacol. 1995 Jun 23;47(1):9-26.
EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.