Banaba (Corosolic acid)

Banaba is a plant that grows in India, Southeast Asia and the Philippines. Traditional uses include brewing tea from the leaves as a treatment for diabetes and elevated blood sugar. Banaba leaf extract contains a triterpenoid compound known as corosolic acid, which has actions in stimulating glucose transport into cells. Studies show that corosolic acid can safely lower blood glucose levels.

In diabetic mice, rats and rabbits, banaba feeding reduces elevated blood sugar and insulin levels to normal. In humans with type II diabetes, banaba extract, for 4-8 weeks, has been shown to be effective in reducing blood sugar levels (5%-30% reduction) and maintaining tighter control of blood sugar fluctuations.

In one study, subjects who took the supplement over a 22-week period had a 30% drop in blood sugar levels. They also averaged a weight loss of 3.2 pounds per month without changing their diet.

For some people, fluctuations in blood sugar and insulin are related to appetite, hunger and various food cravings - particularly craving for carbohydrates such as bread and sweets. By keeping blood sugar and insulin levels in check, banaba helps people to lose weight safely and quickly.

At suggested doses, no adverse side effects are expected from banaba.

Clinical Studies

Study showing CRA has a lowering effect on post-challenge plasma glucose levels in vivo in humans.

Corosolic acid is derived from Lagerstroemia speciosa L. concentrate that is prepared by boiling powder of sliced dry leaves in distilled water. Corosolic acid shows significant glucose transport stimulating activity at very small concentration. A recent study indicates that oral administration of corosolic acid can result in hypoglycemic effects. Stimulation of glucose transport from blood into tissue cells is an essential part in the metabolic process needed to convert dietary components into useful body energy. This hypoglycemic effect of Glucosol™ was studied in hereditary Type II diabetic mice, in which plasma glucose levels increased in the control group. This increase was completely suppressed in the mice given Glucosol™. The results indicate large oral doses of Lagerstroemia speciosa L. produced blood sugar reduction similar to that produced by two units of insulin. The peak reduction occurred two hours after the administration and repetition of the dose. After two hours, Lagerstroemia speciosa L. caused the blood sugar level to remain low (or even lower than the first effect) for more than 4 - 5 hours.


Effects of dietary mulberry, Korean red ginseng, and banaba on glucose homeostasis in relation to PPAR-alpha, PPAR-gamma, and LPL mRNA expressions.

Life Sci. 2005 Nov 12;77(26):3344-54. Department of Food and Nutrition, College of Human Ecology, Sookmyung Women's University, Seoul, Korea.

Mulberry leaf water extract, Korean red ginseng, banaba leaf water extract, and the combination of these herbs fed to mice at the level of 0.5% of the diet significantly increased insulin sensitivity and improved hyperglycemia possibly through regulating PPAR-mediated lipid metabolism.


Effects of malted barley extract and banaba extract on blood glucose levels in genetically diabetic mice

J Med Food. 2004 Winter;7(4):487-90.

This study investigated the therapeutic effects of a malted barley extract (MBE) and of banaba extract on blood glucose, insulin, and other biochemical parameters in genetically diabetic mice (C57BL/KsJ(-) m (+/+) Lepr (db)). The mice were divided into three groups-control, MBE, and banaba-according to supplementation. Both MBE and banaba extracts were orally administered to the animals for 12 weeks at doses of 62.5 mg/kg of body weight and 0.8 mg/kg of body weight, respectively. The body and organ (liver and kidney) weights were not different among groups. Fasting blood glucose was significantly lower in the MBE group compared with the control. Hemoglobin A1c content was significantly lower in the MBE group compared with either the control or banaba group. There was no significant difference in the serum insulin level among groups. The glucose-6-phosphatase activity in kidney was significantly lower in both the MBE and banaba groups compared with the control group, but there was no significant difference between the MBE and banaba groups. Therefore, the results of this study demonstrate that MBE alleviates many of the symptoms of diabetes in genetically obese mice and may offer promise as a therapeutic supplement for the normalization of blood glucose levels in humans with hyperglycemia and have beneficial effects in patients with non-insulin-dependent diabetes mellitus.


Antidiabetic activity of a standardized extract (Glucosol) from Lagerstroemia speciosa leaves - banaba - in Type II diabetics. A dose-dependence study

J Ethnopharmacol. 2003 Jul;87(1):115-7. Judy WV, Hari SP, Stogsdill WW, Judy JS, Naguib YM, Passwater R.
SIBR, Inc., 4112 20th Street West, Bradenton, FL

The antidiabetic activity of an extract from the leaves of Lagerstroemia speciosa standardized to 1% corosolic acid (Glucosol) has been demonstrated in a randomized clinical trial involving Type II diabetics. Subjects received a daily oral dose of Glucosol and blood glucose levels were measured. Glucosol at daily dosages of 32 and 48mg for 2 weeks showed a significant reduction in the blood glucose levels.


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.

The effects of extracts isolated from Lagerstroemia speciosa L. ( banaba ) on glucose transport and adipocyte differentiation in 3T3-L1 cells were studied. Glucose uptake-inducing activity of banaba extract was investigated in differentiated adipocytes using a radioactive assay, and the ability of banaba extract to induce differentiation in preadipocytes was examined by Northern and Western blot analyses. The unique combination of a glucose uptake stimulatory activity, the absence of adipocyte differentiation activity and effective inhibition of adipocyte differentiation induced by IS-IBMX-DEX in 3T3-L1 cells suggest that banaba extract may be useful for prevention and treatment of hyperglycemia and obesity in type II diabetics.


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.

Banaba in the Tagalog name, Lagerstroemia speciosa L., has been used as a folk medicine for a long time among diabetics in the Philippines. Extracts from banaba leaves have been reported to reduce diabetic symptoms in genetically diabetic mice (Type II, KK-Ay). In the present study, female mice of the same strain showing remarkable body weight gain were used to examine the antiobesity effect of dietary banaba extract. Five-week-old female KK-Ay mice were fed a control diet or test diet containing 5% of a hot-water extract from banaba leaves instead of cellulose for 12 wk. Neither group showed any changes in diet intake during the experimental period. Body weight gain and parametrial adipose tissue weight were lowered significantly in the banaba diet group. Blood glucose levels were not suppressed in the banaba diet group, but hemoglobin A1C was found to be suppressed at the end of the experiment. No effects on the serum lipids were observed, but the mice fed banaba extract showed a significant decrease, to 65% of the control level in total hepatic lipid contents. This decrease was due to a reduction in the accumulation of triglyceride. These results suggest that banaba had a beneficial effect on obese female KK-Ay mice.
banaba leaf extract banaba herbs.