Banaba (Lagerstroemia speciosa) is a traditional medicine from India, Southeast Asia and the Philippines that has been used for lowering the blood sugar and for diabetes. The main active component in banaba has been thought to be corosolic acid, and typical formulations on the market are standardized to 1% corosolic acid. Recent research has found another compound called lagerstroemin, an ellagitannin, that is able to cause insulin-like activity (Hattori et al., 2003; Hayashi et al., 2002). In animal studies and unpublished studies in humans banaba has been found to not only regulate blood sugar, but to have the “side effect” of weight loss without dietary alterations (Suzuki et al., 1999). One hypothesis for this is lower fluctuations in blood sugar, and thus lower food cravings (for carbohydrates) which may result in moderate weight loss.
Although published clinical studies are still lacking for banaba, the animal studies have shown good promise that this herbal medicine might be used to lower blood sugar levels in hyperglycermic states and diabetes (Liu et al., 2001; Kakuda et al., 1996; Murakami et al., 1993).
Banaba was studied in a randomized clinical trial for its effect on blood glucose levels in Type II diabetics. A standardized extract of banaba (Lagerstroemia speciosa standardized to 1% corosolic acid; of the brand “Glucosol”) was administered for two weeks, in two different preparations: a softgel, and a dry-powder hard gelatin capsule formulation. Significant reductions in blood glucose levels were found at daily dosages of 32 and 48 mg from banaba administration, and the softgel preparation showed a larger (30% vs. 20%) decrease in blood glucose, indicating a higher bioavailability in the softgel preparation (Judy et al, 2003).
Safety / Dosage
At the recommended dosages of 8-48 mg daily, no side effects have been found for banaba. However, at higher dosages symptoms associated with low blood sugar (headache, dizziness, fatique) may be expected.
1.Hattori K, Sukenobu N, Sasaki T, Takasuga S, Hayashi T, Kasai R, Yamasaki K, Hazeki O. Activation of insulin receptors by lagerstroemin. J Pharmacol Sci. 2003 Sep;93(1):69-73.
2.Hayashi T, Maruyama H, Kasai R, Hattori K, Takasuga S, Hazeki O, Yamasaki K, Tanaka T. Ellagitannins from Lagerstroemia speciosa as activators of glucose transport in fat cells. Planta Med. 2002 Feb;68(2):173-5.
3.Judy WV, Hari SP, Stogsdill WW, Judy JS, Naguib YM, Passwater R. Antidiabetic activity of a standardized extract (Glucosol) from Lagerstroemia speciosa leaves in Type II diabetics. A dose-dependence study. J Ethnopharmacol. 2003 Jul;87(1):115-7.
4.Kakuda T, Sakane I, Takihara T, Ozaki Y, Takeuchi H, Kuroyanagi M. Hypoglycemic effect of extracts from Lagerstroemia speciosa L. leaves in genetically diabetic KK-AY mice. Biosci Biotechnol Biochem. 1996 Feb;60(2):204-8.
5.Liu F, Kim J, Li Y, Liu X, Li J, Chen X. An extract of Lagerstroemia speciosa L. has insulin-like glucose uptake-stimulatory and adipocyte differentiation-inhibitory activities in 3T3-L1 cells. J Nutr. 2001 Sep;131(9):2242-7.
6.Murakami C, Myoga K, Kasai R, Ohtani K, Kurokawa T, Ishibashi S, Dayrit F, Padolina WG, Yamasaki K. Screening of plant constituents for effect on glucose transport activity in Ehrlich ascites tumour cells. Chem Pharm Bull (Tokyo). 1993 Dec;41(12):2129-31.
7.Suzuki Y, Unno T, Ushitani M, Hayashi K, Kakuda T. Antiobesity activity of extracts from Lagerstroemia speciosa L. leaves on female KK-Ay mice. J Nutr Sci Vitaminol (Tokyo). 1999 Dec;45(6):791-5.
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