(NaturalNews) Yacon leaf (Smallantus sonchifolius) is an herb that has become popular in recent years due to a few controlled medical studies showing the positive effects of yacon leaf on diabetic rats. The herb is used in South America to control blood sugar. Some commercial green superfood formula makers list yacon leaf as an ingredient. Yacon is considered a superfood because it it high in flavanoids, fructooligosaccharides, and antioxidants. The interest in yacon leaf motivated a team of researchers in 2011 to study the long-term effects of yacon leaf extract. They experimented with yacon leaf tea on diabetic rats for ninety days. The results were that long-term usage of yacon leaf caused kidney damage in the rats. Yacon leaf is no longer being considered as a possible therapy for diabetes.
The initial clinical study involving yacon leaf and diabetes showed great promise
The Journal of Ethnopharmacology published a clinical study in 2001 which involved administering a decoction [sic] of yacon leaf tea to rats which had been induced with diabetes. The rats were either fed a 10 percent solution of yacon tea by injection or by a feeding tube. A single dose was enough to reduce the blood glucose levels in the control rats, but had no effect on the diabetic rats. However, when the rats' water bottles were filled with yacon tea instead of water for thirty days, and the rats were given free access to the water bottles, the blood glucose levels of the diabetic rats dropped significantly. After thirty days on yacon leaf tea, the diabetic rats demonstrated a healthy weight loss. Also, their insulin levels and urinary tract markers had improved. The scientists conducting the study believed that yacon leaf tea did have a positive effect on insulin levels, and were very encouraged about its possible use in human diabetics.
A second clinical study involving diabetic rats furthered the enthusiasm for yacon leaf
A second team of scientists decided to experiment on diabetic rats with a variety of yacon leaf extracts in 2010. Published in Chemico-Biological Interactions, this clinical study tested blood glucose and insulin levels of diabetic rats with five different strengths of yacon leaf extract for eight weeks. After eight weeks on yacon leaf extract, the insulin and glycemic levels in the diabetic rats were under control. Again, the researchers were quite enthusiastic about the possibility of yacon leaf in the treatment of diabetes.
A long-term study of yacon leaf in 2011 resulted in disappointing news
In 2011, a team of Brazilian scientists decided to test the long-term effects of yacon leaf extract on diabetic rats, citing the above studies. The scientists chose yacon leaf tea (infusion), leaf-rinse extract, and a polar extract for the study. This toxicity study lasted for 90 days. At the end of the study, both the yacon leaf tea and the leaf-rinse extract had caused kidney damage, and the rats' blood glucose levels had risen. The scientists decided that the positive effects of yacon leaf were reversible, and that yacon leaf contained kidney-damaging levels of terpenoids. They could not recommend yacon leaf in the treatment of diabetes.
Sources for this article include:
Pubmed.gov, "Hypoglycemic effect of the water extract of Smallantus sonchifolius (yacon) leaves in normal and diabetic rats." M.J. Avbar, et al. Journal of Ethnopharmacology February 2001; 74(2):125-32. http://www.ncbi.nlm.nih.gov/pubmed/11167030
Pubmed.gov, "Hypoglycemic activity of leaf organic extracts from Smallantus sonchifolius: Constituents of the most active fractions." S.B. Genta, et al. Chemico- Biological Interactions April 2010; 185(2): 143-52. http://www.ncbi.nlm.nih.gov/pubmed/20211156
Pubmed.gov, "Renal toxicity caused by oral use of medicinal plants: the yacon example." R.B. de Oliveira, et al. Journal of Ethnopharmacology January 2011; 133(2): 434-41. http://www.ncbi.nlm.nih.gov/pubmed/20951787