Banaba is a plant belonging to the genus Lagerstroemia, native to India and South East Asia. It’s most commonly known as Crepe Myrtle, an attractive flowering tree that grows well in warmer climates of the southern United States.  The leaves of banaba, specifically Lagerstroemia speciosa, have a long history of being used for medicinal purposes. In particular, they have been used to lower blood sugar levels in diabetics. The first known scientific study goes all the way back to 1940.¹

Since then there have been numerous studies on its efficacy in reducing blood sugar levels and the overall conclusions have been that it does so effectively and safely. The fact that it’s natural, and that no adverse effects have been noted in humans², makes it worth considering as an alternative therapy for lowering blood sugar levels. When one considers the negative side effects of conventional diabetic treatments, which include stomach upsets, weight gain, kidney failure, liver failure, fatigue, dizziness, skin rashes and itching, bloating, diarrhea and more³, banaba leaf extract becomes an attractive option.    

How It Works

Banaba leaves contain corosolic acid, which appears to be the main ingredient responsible for lowering blood sugar. They also contain ellagitannins, which have also been shown to help reduce blood sugar levels.

These ingredients do this in a number of ways:

• by improving the cells’ ability to absorb glucose from the bloodstream.
• by reducing the resistance to insulin in the cells.
• by impairing the breakdown of starches and sucrose into glucose, slowing its assimilation into the bloodstream.
• by inhibiting the conversion of proteins into glucose, a process called gluconeogenesis.
• by regulating the metabolism of fats and oils.

All of the above processes have the effect of slowing the rate at which glucose is absorbed into the bloodstream and in this way lowering overall blood sugar levels.

Results

Here are the results from just a few human studies on banaba leaf extracts; there are many more involving both humans and animals.

According to a report quoted on WebMed, subjects given banaba leaf extract had a 10% reduction in blood sugar levels in just two weeks.⁴

One research study showed that subjects given a soft gel capsule containing banaba leaf extract experienced a 30% lowering of blood sugar.⁵

 A 2006 study reported that subjects given a banaba leaf extract had an average reduction of blood sugar of  12% and a weight loss of three pounds in a two week period.⁶

 Yet another study showed that subjects given a banaba leaf extract for a period of one year had a significant reduction in overall blood sugar levels and experienced no adverse reactions.⁷

 In addition to helping lower blood sugar levels, one study showed that banaba leaf extract may also have benefits for the heart.⁸

^Conclusion

It’s abundantly clear that banaba leaf extracts have a long and safe history of human use and that it’s effective in helping to lower blood sugar levels. This makes it an attractive alternative treatment option for people suffering from Type 2 diabetes. Although there are clear indications that it is safe to use, people suffering from chronic diseases, like heart and kidney disease,  as well as pregnant and breastfeeding women, should first seek the advice of their medical professional before using. If you are already taking medication for diabetes, do not stop unless you’ve first discussed it with your medical professional.

References

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3468018/
2. Judy, W. V., Hari, S. P., Stogsdill, W. W., Judy, J. S., Naguib, Y. M., & Passwater, R. (2003).
   Antidiabetic activity of a standardized extract (Glucosol™) from Lagerstroemia speciosa leaves type 2 diabetics: A dose-dependence study. Journal of Ethnopharmacology, 87(1), 115-117.
3. https://www.diabetes.co.uk/features/diabetes-medication-side-effects.html and
4. https://www.canadianinsulin.com/articles/side-effects-type-2-diabetes-medications/
5. https://www.webmd.com/vitamins/ai/ingredientmono-1089/banaba
6. https://www.sciencedirect.com/science/article/pii/S0378874103001223?via%3Dihub
7. Tsuchibe S, Kataumi S, Mori M, Mori H. An inhibitory effect on the increase in the postprandial glucose by banaba extract capsule enriched corosolic acid. Journal for the Integrated Study of Dietary Habits. 2006;17:255–259.
8. Ikeda Y, Noguchi M, Kishi S, et al. Blood glucose controlling effects and safety of single and long-term administration on the extract of banaba leaves. Journal of Nutrition & Food. 2002;5:41–53
9. Ichikawa H, et al. Lagerstroemia speciosa extract inhibit TNF-induced activation of nuclear factor-kappaB in rat cardiomyocyte H9c2 cells . J Ethnopharmacol. (2010)