Banaba (Lagerstroemia speciosa) is a tree from Southeast Asia whose leaves are used for blood sugar. Corosolic acid is one of its active compounds (Stohs 2012).
Also known as: banaba leaf, Lagerstroemia speciosa, corosolic acid, crepe myrtle.
A 12-week trial used 500 mg twice a day (López-Murillo 2022). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
What studies show: in 24 people with metabolic syndrome, 12 weeks of banaba lowered systolic blood pressure, fasting blood sugar, triglycerides and insulin output from where they started, and 8 of 12 no longer met the metabolic syndrome definition (López-Murillo 2022). This was a very small trial, and its abstract compares results with baseline rather than reporting a clear difference from placebo. A 2012 review reports that pure corosolic acid lowered blood sugar within 60 minutes in people (Stohs 2012).
Safety: the 2012 review found no side effects reported in animal studies or controlled human trials (Stohs 2012). People on diabetes medicines should ask their prescriber first, since banaba is taken to lower blood sugar. The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for banaba that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
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