Stevia, a perennial plant original from Paraguay, is today well known in the world for its sweetener properties as it contains steviosides that are between a hundred-fifty to three hundreds times as sweet as table sugar. It has been used for this purpose, and also medicinally for hundreds of years in certain regions of South America. The stevioside is contained in the green leaves of the plant . (Sahelian & Gates, 2000, p38).
Some of the medicinal properties Stevia allege to have are antibacterial, antidiabetic, antiemetic, anti-inflammatory, antiseptic, diuretic, hypoglycemic vasodilator. (Duke et al 2002, p.697).
Many studies have been conducted in order to discover the properties of the active substances found in the Stevia, and many of them found interesting results, especially its antidiabetic power.
In 2012, a study held in India with induced diabetic rats treated with powder and polyphenols extract of stevia leaves show up a reduction of blood glucose and AST/ALT (aspartate aminotransferase / alanine aminotransferase), while the insulin level were increase. (Shivanna et al 2012).
Another study, held during 28 days, where 24 rats were divided in four groups, one treated with an aqueous extract of Stevia leaves, the second one with an ether extract, a third group with a metanolic extract and the fourth being the control group. The daily dose was of 2.0g/Kg and after 28 days the results showed a decreased of blood sugar levels in the groups taking stevia extract, whereas no significant reduction of AST and ALT level were observed. This study concluded that Stevia could decrease the glucose levels in the blood (Kujur et al 2010).
In 2011, studying the effects of benzene/acetone Stevia leaves extract on diabetic induce rats for a period of ten days, administrating 200 and 400 mg/Kg per day, result in a lowering of the blood glucose levels. They concluded that Stevia has antidiabetic effects and acknowledged that to the presence of the stevioside and rebaudioside A present in Stevia leaves (Misra et al 2011).
A 2005 study from Taipei medical university in Taiwan conducted a trial of fifteen days observing stevioside effects on glucose and insulin in two groups of rats induced with two different types of diabetes. Their conclusion was that steviosides were able to regulate blood glucose levels by enhancing insulin secretion and utilization in insulin-deficient rats. They find out that insulin utilization was a consequence of the decreasing of PEPCK gene expression in rat liver caused by steviosides slowing down gluconeogenesis (Chen et al 2005).
In Denmark Aarhus University Hospital, two studies were held in 2004. The first one studied the effect of Rebaudioside A on insulin and showed in its results that Rebaudioside A induced insuline stimulation with high glucose disappearing in absence of extracellular Ca2+. The conclusion was that Rebaudioside A possesses insulinotropic effects that can be utilized in the treatment of type 2 diabetes (Abudula et al 2004).
The second study experimented on twelve type 2 diabetic patients stevioside effects. It was a paired, crossover study where the study group was given 1g of stevioside added in a standard meal and the control group had 1g of maize starche added to its meal. Blood samples were taken 30 minutes before and 240 minutes after ingestion and the result showed a decrease in the glucose response curve by 18% and an increase of 40% of the insulinogenic index of the study group compared to the control group. Stevioside decrease postprandial blood glucose levels. So they conclude that stevioside may be beneficial in the treatment of type 2 diabetic patients (Gregersen et al 2004).
Those many evidence show us the beneficial value that stevia has in the effective treatment of diabetes by reducing glucose levels and increasing insulin production. A generalization of the use of this magnificent plant, promise us with greater beneficial uses such as the ones for diabetes but also for hypertension, cholesterol or even preventing cardiac problems.
References 1. Abudula R, Jeppesen PB, Rolfsen SE, Xiao J, Hermansen K. (Oct 2004). Rebaudioside A potently stimulates insulin secretion from isolated mouse islets: studies on the dose-, glucose-, and calcium-dependency. Metabolism, volume 53, pp1378, 1381.
2. Chen TH, Chen SC, Chan P, Chu YL, Yang HY, Cheng JT. (2005). Mechanism of the hypoglycemic effect of stevioside, a glycoside of Stevia rebaudiana. PubMed, PMID: 15729617.
3. Duke,J. Bogenschutz-Godwin, M J. Ducellier, J. & Duke, P A. (2002). Handbook of medicinal herbs (2nd Ed.).USA: CRC Press LLC.
4. Gregersen S, Jeppesen PB, Holst JJ, Hermansen K. (Jan 2004). Antihyperglycemic effects of stevioside in type 2 diabetic subjects. Metabolism, volume 53, pp 73, 76. PMID: 14681845
5. R. S. Kujur, Vishakha Singh, Mahendra Ram, Harlokesh Narayan Yadava,1 K. K. Singh,2 Suruchi Kumari, and B. K. Roy. (2010). Antidiabetic activity and phytochemical screening of crude extract of Stevia rebaudiana in alloxan-induced diabetic rats. Pharmacognosy research, volume 2 (4), pp.258 263.
6. Himanshu M, Manish S, Narendra S, Darshana M, B. K. Mehta,& D. C. Jain. (2011). Antidiabetic activity of medium-polar extract from the leaves of Stevia rebaudiana Bert. (Bertoni) on alloxan-induced diabetic rats. Journal of pharmacy & bioallied sciences, volume 3 (2). pp. 242 248.
7. Sahelian R & Gates D. (2000). Suddenly Stevia. Better nutrition, volume 62. pp. 38 41.
8. Shivanna N, Naika M, Khanum F, Kaul VK. (2012). Antioxidant, anti-diabetic and renal protective properties of Stevia rebaudiana. Journal of diabetes and its complications, PubMed. PMID: 23140911.
T. Ienco January 2013