Is Banaba Effective in Lowering Blood Glucose?

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Makensi Johnson
Makensi Johnson

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.

Clinical Evidence:
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.,-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.

Recommend0 recommendationsPublished in College of Pharmacy, Virtual Poster Session Spring 2021


  1. Hello Makensi and Vanessa – what are the two main things you learned from preparing and developing this topic?

    1. Hello Dr. Shane-McWhorter. The first thing I learned from doing this project is how difficult it can be to find quality, human research on dietary supplements. I think this is an important point to discuss with patients when they inquire about using a supplement. Additionally, I learned how popular diabetes is as a reason for supplement use. I wonder if this is due to the prevalence of diabetes in our country, the high cost of diabetes medications, or a combination of the two.

    2. One main thing I learned from completing this project is a little bit about the process of how research is done on herbal supplements and finding what parts are effective for treatment or not. Within one of the articles I read it went into great depth on spectroscopy of extracts and testing those within animals and humans. I personally do not feel like we get much information on the first steps of researching products so it was really cool to read that. I also learned that finding high quality articles on herbal supplements can be very difficult due to much of the research being conducted within animals, as well as human studies having very small sample sizes and not much regulation. It is a lesson to keep in mind when counseling patients on supplement use within certain disease states throughout my career.

  2. Interesting topic. What can be learned from the acute glucose lowering effect in the first study? What would you say to a patient that is interested in using banaba? Is banaba available in this country and any ideas about cost?

    1. Information within the first study states that acute glucose lowering effects were seen after around 60 to 120 minutes reaching what the authors found as statistically significant at 90 minutes. The study did not include data as to what was considered statistically significant. Based on this information given within the study we can learn that corosolic acid extracted from banaba has an acute glucose lowering effect, however based on study limitations more studies need to be conducted to further evaluate serum glucose levels with banaba use.

      If a diabetic patient is interested in using banaba, I would share the positive conclusions in glucose lowering effects with the additional limitations of the studies, concluding that there is insufficient evidence in use of this supplement within humans. As a pharmacist I would also do my best to counsel the patient on the drug interactions between other anti-diabetic and anti-hypertensive medications. I would tell the patient if they are still considering use of banaba that they should talk to their doctor before stopping or starting any medications including supplements.

      Banaba extract can be found to purchase in many online sources such as Amazon and Walmart for roughly $10-20 per bottle of 100.

  3. Hi Vanessa and Makensi! I really enjoyed your poster!
    What formulation do patients typically take Banaba in? Is it the liquid extract that is encapsulated or the powder from the shrubs?

    1. Hey Rilee – Based on one of the studies we reviewed for our topic we found that the soft gel with liquid extract was most efficient in lowering blood glucose levels. Based on this and what I have seen on the market patients typically take this formulation. If a patient is taking a different formulation I would recommend switching for higher efficacy.

  4. Hello Makensi and Vanessa!
    What recommendations would you make to a patient who wants to start Banaba soft gel capsules to lower their blood glucose levels with other diabetes medications they’re taking? (Metformin, insulin, etc.)

    1. Hi Ryley. I would have them have a conversation with their doctor that they are interested in starting banaba. They might not need additional blood glucose lowering if they are on other medications. If they choose to start banaba in addition to their other medications, I would have them monitor their blood glucose to make sure they do not have a hypoglycemic event.

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