Gymnema sylvestre extract is obtained from an herb native to southern and central India. It is a woody climbing plant that grows in tropical forests that has been used medicinally in India for over 2,000 years. Gymnema sylvestre has a very bitter taste and disrupts the ability to taste sweetness. It has primarily been used to reduce blood glucose levels, but has also been used to reduce appetite and decrease inflammation. It has been reported to have anti-microbial and anti-viral activity. The plant constituents that are responsible for the medicinal effects of Gymnema sylvestre are gymnemic acids. A Wisconsin-based biotechnology company, called Ayurvedic-Life International has patented a Gymnema sylvestre extract, called OSA.
Mechanism of Action
Multiple animal studies demonstrate that Gymnema sylvestre extract reduces blood glucose levels. Additionally, two different studies conducted in diabetic rats suggest Gymnema sylvestre extract stimulates the growth of insulin-secreting cells. Results from animal studies provide evidence that Gymnema sylvestre extract reduces blood glucose levels by decreasing glucose absorption in the gut, promoting glucose uptake by cells in the body and by increasing insulin levels.
Diabetes Studies
A study published in the October 1990 issue of the "Journal of Ethnopharmacology" reported that 400 mg/day of Gymnema sylvestre extract reduced insulin requirements, decreased fasting blood glucose levels and decreased average blood glucose concentrations in type 1 diabetic patients. A second study conducted by the same researchers and published in the same issue of the "Journal of Ethnopharmacology" reported that Gymnema sylvestre extract decreased fasting blood glucose levels and average blood glucose concentrations and increased serum insulin levels in type 2 diabetic patients. A study published in the September 2010 issue of "Phytotherapy Research" reported that the Gymnema sylvestre extract, OSA significantly reduces blood glucose levels and increases serum insulin levels in type 2 diabetics.
Weight Loss Studies
Gymnema sylvestre extract has been reported to decrease appetite, improve weight loss and decrease serum lipid levels. A study in the journal "Diabetes, Obesity and Metabolism" reported that Gymnema sylvestre extract in combination with hydroxycitric acid and niacin-bound chromium reduced body weight in obese subjects. A study published in the "Biological and Pharmaceutical Bulletin" found that Gymnema sylvestre extract decreased lipid levels in rats fed a high-fat diet.
Anti-inflammatory Studies
In other countries Gymnema sylvestre extract has been used to treat arthritis and gout. A few studies in mice and rats suggest Gymnema sylvestre extract reduces inflammation and swelling. No human studies have been conducted that have evaluated the effects of Gymnema sylvestre extract on inflammatory responses.
Toxicity
Side effects of Gymnema sylvestre extract have not been reported. A toxicity study in a Japanese journal that was conducted in rats did not find any adverse effects associated with supplementing their diets with up to 1 percent of Gymnema sylvestre extract powder for 52 weeks. Because Gymnema sylvestre extract reduces blood glucose levels it could cause hypoglycemia.
References
- Thorne.com: Gymnema sylvestre Monograph
- PubMed: Use of Gymnema sylvestre Leaf Extract in the Control of Blood Glucose in Insulin-dependent Diabetes Mellitus
- Pubmed: Antidiabetic Effect of a Leaf Extract from Gymnema sylvestre in Non-insulin-dependent Diabetes Mellitus Patients
- PubMed: 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
- PubMed: Effect of Administration with the Extract of Gymnema sylvestre R. Br Leaves on Lipid Metabolism in Rats
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