Banaba is a species of Crepe Myrtle, an ornamental Asian shrub with pink, white, or purple crinkled petals. Scientifically banaba is known as Lagerstroemia speciosa, originating from the Lythraceae family. It is commonly found in India, the Philippines, and Southeast Asia. Various extracts of banaba have been used in folk medicine to treat diabetes for many years. The first published research study on banaba dates back to 1940.
A double-blind, cross-over randomized control trial was conducted by Fukushima and colleges to examine effectiveness of corosolic acid, an active extract of banaba, on post challenge plasma glucose levels in humans. Thirty-one subjects were orally administered 10 mg corosolic acid (CRA) or placebo before the 75-g oral glucose tolerance test. Most subjects within the study had a diagnosis of diabetes, and others had impaired glucose tolerance. The primary outcomes were plasma glucose and serum insulin levels at baseline, 30, 60, 90, 120, and 180 minutes after administration. Plasma glucose and serum insulin levels were measured by glucose oxidase methods and enzyme immunoassay. Subjects treated with CRA showed lower glucose levels from 60 minutes until 120 minutes and reached statistical significance at 90 minutes. The authors considered the hypoglycemic effects due to polyphenols and other factors within the extract. They concluded that corosolic acid has a lowering effect on post challenge plasma glucose in humans, however further studies are needed to explain the mechanism of action for this effect.
In a study by Judy and colleges, two different formulations of lagerstromia speciosa (banaba) were assessed for blood glucose lowering effects in patients with type 2 diabetes. Soft gel capsules and dry powder filled hard gelatin capsules were made from extracts taken from banaba plants in the Philippines. 56 patients with type 2 diabetes were screened, and 10 patients were chosen and randomized into either a soft gel or hard gelatin capsule group. The primary outcome being assessed was fasting blood glucose reduction. Each group was given 15 days of 16, 32, and 48 milligram capsules with a 10 day wash out period. The soft gel group showed a 30% reduction at the highest dose of 48 mg and a p-value of 0.002. The hard gel group showed a 20% reduction at the highest dose and a p-value of 0.001. The authors concluded that as the dose of banaba increased the reduction in blood glucose increased, as well as the soft gel formulation yielded a better response.
Based on our research, the reviewed clinical studies convey that banaba may lower blood glucose levels. Due to very few human studies and a high number of limitations, we found that there is not enough human data to make a conclusive statement on banaba’s blood glucose lowering effects. If patients want to use banaba for hypoglycemic effects, it is best to consider finding a soft gel product with a USP seal. Further studies should be conducted with a larger population, efforts to mitigate bias, and longer study length to provide confidence within the study. We recommend that patients discuss with their doctors before stopping or starting any new medications or supplements. Pharmacists should provide council on efficacy and safety for alternative and prescription treatments in diabetes.
1. Natural Medicines Comprehensive Database.
https://naturalmedicines-therapeuticresearch-com.ezproxy.lib.utah.edu/databases/food,-herbs-supplements/professional.aspx?productid=1089. Accessed on July 19th, 2021.
2. Judy WV, Hari SP, Stogsdill WW, et al. Antidiabetic activity of a standardized extract (Glucosol) from Lagerstroemia speciosa leaves in Type II diabetics. A dose-dependence study. J Ethnopharmacol 2003;87:115-7
3. Fukushima M, Matsuyama F, Ueda N, et al. Effect of corosolic acid on postchallenge plasma glucose levels. Diabetes Research and Clinical Practice. 2006;73(2):174-177. doi:10.1016/J.DIABRES.2006.01.010
4. Stohs SJ, Miller H, Kaats GR. A review of the efficacy and safety of banaba (Lagerstroemia speciosa L.) and corosolic acid. Phytotherapy Research. 2012;26(3):317-324. doi:10.1002/ptr.3664
5. Kinsey, D. C. (2021, June 4). Banaba leaves: Health Benefits, Uses, side EFFECTS, DOSAGE. Ben’s Natural Health. https://www.bensnaturalhealth.com/blog/diabetes-health/banaba/.