Gymnema Sylvestre herb and extract health benefit for weight loss and blood sugar control, dosage and side effects, safety, toxicity

Leaves of the Gymnema sylvestre plant have been used to treat diabetes mellitus and obesity for a long time. Gymnema leaf has been used traditionally in India for centuries and has been shown in research to support healthy glucose metabolism and healthy pancreatic function.

Additional herbs used for blood sugar control
Throughout history medicine men and women have stumbled upon herbs that treat various health issues. Some of the popular herbs used for diabetes include Bitter Melon (Momordica charantia), Fenugreek (trigonella foenum graecum), Gymnema Sylvestre, Ivy Gourd (Coccinia indica), Nopal or Prickly Pear Cactus (Opuntia streptacantha), Ginseng, Aloe Vera, Russian Tarragon (Artemisia dracunculus), and Garlic (Allium sativum).

How is this herb available?
You can find gymnema in the form of capsules or tablets sold by a number of online companies and health food stores. There are dozens of products on the market in different dosages and extract concentrations. Here are some examples:

Gymnema Sylvestre 400 mg (leaf) 60 tablets available at Physicians Formulas web site
Gymnema Leaf Standardized Extract 25% 260 mg, 60 capsules

Gymnema Sylvestre and diabetes studies
Gymnema sylvestre is regarded as one of the plants with potent anti diabetic properties.

Structural alterations in pancreatic islets in streptozotocin-induced diabetic rats treated with of bioactive additive on the basis of Gymnema sylvestre
Morfologiia. 2008.
The structural alterations in pancreatic islets in streptozotocin-induced diabetic rats were studied after the administration of Gymnema sylvestre extract or its composition. Prophylactic administration tended to restore the area occupied by B-endocrinocytes in the pancreatic islets. These results indicate the equal potency of the composition and extract of Gymnema sylvestre to induce the regeneration of B-endocrinocytes.

Characterisation of the insulinotropic activity of an aqueous extract of Gymnema sylvestre in mouse beta-cells and human islets of Langerhans.
Cell Physiol Biochem. 2009; Liu B, Asare-Anane H, Al-Romaiyan A, Amiel SA, Persaud SJ. Beta Cell Development & Function Group and Division of Gene & Cell Based Therapy, King's College London, UK.
We have now examined the effects of a novel Gymnema sylvestre extract (termed OSA) on insulin secretion from the MIN6 beta-cell line and isolated human islets of Langerhans. Our data indicate that low concentrations of the Gymnema sylvestre isolate OSA stimulate insulin secretion in vitro, at least in part as a consequence of Ca2+ influx, without compromising beta-cell viability. Identification of the component of the OSA extract that stimulates regulated insulin exocytosis, and further investigation of its mode(s) of action, may provide promising lead targets for Type 2 diabetes therapy.

Weight loss
This plant is traditionally used for controlling obesity in the form of Gymnema tea. The active compound of the plant is a group of acids termed as gymnemic acids. A human study conducted in India in 2004 shows this herbal extract to have promise in terms of weight loss.

Effects of a natural extract of (-)-hydroxycitric acid (HCA-SX) and a combination of HCA-SX plus niacin-bound chromium and Gymnema sylvestre extract on weight loss.
Diabetes Obes Metab. 2004; Preuss HG, Bagchi D, Bagchi M, Satyanarayana S. Department of Physiology and Biophysics, Georgetown University Medical Center, Georgetown, Washington, DC, USA.
The efficacy of optimal doses of highly bioavailable (-)-hydroxycitric acid (HCA-SX) alone and in combination with niacin-bound chromium (NBC) and a standardized Gymnema sylvestre extract (GSE) on weight loss in moderately obese subjects was evaluated by monitoring changes in body weight, body mass index (BMI), appetite, lipid profiles, serum leptin and excretion of urinary fat metabolites. HCA-SX has been shown to reduce appetite, inhibit fat synthesis and decrease body weight without stimulating the central nervous system. NBC has demonstrated its ability to maintain healthy insulin levels, while GSE has been shown to regulate weight loss and blood sugar levels. A randomized, double-blind, placebo-controlled human study was conducted in Elluru, India for 8 weeks in 60 moderately obese subjects. Subjects were randomly divided into three groups. Group A was administered HCA-SX 4667 mg, group B was administered a combination of HCA-SX 4667 mg, NBC 4 mg and GSE 400 mg, while group C was given placebo daily in three equally divided doses 30-60 min before meals. All subjects received a 2000 kcal diet/day and participated in supervised walking. At the end of 8 weeks, body weight and BMI decreased by 5-6% in both groups A and B. Food intake, total cholesterol, low-density lipoproteins, triglycerides and serum leptin levels were significantly reduced in both groups, while high-density lipoprotein levels and excretion of urinary fat metabolites increased in both groups. A marginal or non-significant effect was observed in all parameters in group C. The present study shows that optimal doses of HCA-SX and, to a greater degree, the combination of HCA-SX, NBC and Gymnema sylvestre extract can serve as an effective and safe weight-loss formula that can facilitate a reduction in excess body weight and BMI, while promoting healthy blood lipid levels.

Decreased bodyweight without rebound and regulated lipoprotein metabolism by gymnemate in genetic multifactor syndrome animal.
Mol Cell Biochem. 2007; Luo H, Kashiwagi A, Yamada K. Department of Pathophysiological and Therapeutic Science, Division of Medical Biochemistry, Faculty of Medicine, Tottori University, Yonago, Japan.
The aim of this work was to find obesity control method without rebound. In our previous studies, gymnemate extracted from Gymnema sylvestre, inhibited oleic acid absorption. The effect of gymnemate on obesity in rats was investigated. Supplementation with gymnemate promoted weight loss by its ability to reduce hyperlipidemia, which was no withdrawal rebound: an important discovery. Supplementation with gymnemate is a novel therapeutic tool for weight management, especially in multifactor syndrome.

Side effects, toxicity, safety issues
No major side effects have been reported in the medical literature as of May 2009.

Gymnema sylvestre leaf extract: a 52-week dietary toxicity study in Wistar rats
Shokuhin Eiseigaku Zasshi. 2004; Ogawa Y, Sekita K, Umemura T, Ono A, Kawasaki Y, Uchida O, Matsushima Y, Inoue T, Kanno J. Center for Biological Safety and Research, National Institute of Health Sciences, Kamiyoga, Setagaya-ku, Tokyo, Japan.
A 52-week study of oral-repeated-dose toxicity for the extraction powder of Gymnema sylvestre, Indian-native genus, Metaplexis japonica, was conducted in both genders of Wistar rats. The rats were administered a graded dose of GS at 0.01, 0.10 and 1.00% of basal powder diet, along with a group fed solely with the basal powder diet without GS, for 52 weeks. At 26 weeks, for an intermediate examination, and 52 weeks, for the final examination, animals were subjected to hematology, serum chemistry, and pathological examination. None of the animals died in the period up to 52 weeks. No exposure-related changes in body-weight, in the food consumption, in the hematological examinations, or in the serum biochemical examinations were recognized. No histopathological alterations were seen. Thus, it was concluded that there was no toxic effect in rats treated with Gymnema sylvestre at up to 1.00% in the diet for 52 weeks. The no-observable-effect level from this study is 1% Gymnema sylvestre, i.e., 504 mg/kg/day for male and 563 mg/kg/day for female as mean daily intake, for 52 weeks.

Chemical constituents from the leaves
Gymnemic acids are the primary constituents. Gymnemagenin is the deacylated aglycone of gymnemic acid.

Chemical constituents from the stem of Gymnema sylvestre herb
Zhong Yao Cai. 2008;
Research on chemical constituents from stem of Gymnema sylvestre
College of Pharmaceutical, Guangxi Traditional Chinese Medical University, Nanning, China.
Eight compounds were isolated and identified as fallows: Conduritol A, 1-Heptadecanol, Stigmasterol glucoside, 1-Quercitol, 1-Octadecanol, Potassium nitrate, Lupeol cinnamate, Stigmasterol.

Interactions with herbs
Does gymnema interact with eurycoma longifolia herb?
    Eurycoma is a potent herb and should be taken by itself the first few times it is used, if no problems then it can be combined with GS herb.